MIL cannot be on time!

Tell her that if she can't be arsed to be on time then you will be going without her. Then follow through with it. That is the only way she might learn.

Next time don't go to her house, agree to pick her up at the end of the road at 9.30am. Tell her if she's not there you will presume she has changed her mind or is making her own way there. Send a text at 9.00am saying the same thing. If she hasn't turned up by 9.40am leave. If she texts back saying she's running late then reply, okay we'll see you there then leave her to make her own way there.

Nope, this won’t work. Because even if you gave yourself an additional hour then you will just be distracted by 101 chains of thought and actions for that hour.

so both of you would make an arrangement, date and time, with a friend to pick you up and you'd just... let them wait because you're chilling?

You'd last precisely zero trips with me, chilled or not, because if we've arranged a time, you're there or you don't come. If it's a "see you there, sometime" that's a whole different arrangement

This is what I would do. I have friends who are often late (one rang up once thinking they must have gone to the wrong place as I wasn’t already there!) but they’re lovely friends and it’s not personal so I just make sure I make plans where it feels ok to be kept waiting. Friends who regularly cancel on me, I continue to be friendly with but only meet in group situations where my plans are not impacted when they pull out last minute, as lots of us are doing it.

I'm always early but I will wait in the car/read a book or something

So say I'm driving to Manchester for an appointment at 3pm
If it takes 45 mins, I allow 1hr for the drive. Then 15 mins for parking/walking. Which means I need to leave at 1.45pm
Then I work backwards from that for everything like shower, hair, makeup, if I need to get fuel...
it's never failed me!

I'll bet she does. Because you sit there and wait. If you drove off and said you'd meet her there she might start being on time.

My SIL is the same. Wants to meet for a dog walk, then leaves me and my dogs waiting in the cold while she gets herself to wherever. She never switches her phone on, rarely takes it with her, so cannot be contacted.
These days I just don’t wait. If she’s not there on time she is on her own. Shame as her dog is lovely.

i would have left way before then telling her to meet you later.
No transport? not your problem

It's on you for waiting for her TBH.

Don't participate in this silly fuckery and then complain about it.

Drive off, send a text saying you'll meet her there.

Or accept your role in it and stop acting like it's something that is happening to you.

Let her set the time to collect her, leave immediately if she isn’t ready. Let her find her own way if she’s not ready on time. Don’t change your plans to accommodate her tardiness.

I've got a SIL like that. I'll arrange to go and pick her up, at a time she's chosen, but then she's always still late. Recently, she opened the door and said she'd be 3 minutes, she had to have her tablets first! She left me sitting in the car - she never asks anyone in, not even her adult kids. She came out of her house 25 minutes later, then we were late for our booked table. It's the absolute height of bad manners.

Since she is more than capable of driving and was clearly going to be some time you are mugs to have sat and waited for her.
I'm guessing it didn't bother your partner one bit so in future I'd refuse to pick her up at all.

Constant lateness really winds me up! Its the epitome of rudeness, expecting others just to hang around waiting for you! I cut people like this out of my life where possible because i can't enjoy going out with or meeting up with them when they have already given me the hump by being late!

This

I just don't understand why you waited. This is not a one-off thing, it's rude and disrespectful and I would have just left without her today, she could either stay home or make her own way there.

I'd just leave. You're not ready. We're going to the shop without you.

My family are sticklers for time keeping. When I was a kid if I wasn't ready by the front door at the specified time - we either weren't going or I was being left behind. It only takes once to learn the lesson.

Honestly I would just go without her in future if she's not ready at the stated time. She won't like it of course, but that's on her. I did it once with my daughter as I was sick of her faffing getting ready for college making me late for work which was being unfavourably commented on. Despite all the talk, she continued to be late. Her outrage that morning when she phoned me once she realised I'd left without her! She never did it again. However of course it will be different for you as she's your MIL.

@Happybakers don't try, 100% make sure that meeting there is what you do. Only agree otherwise if your MIL has had something such as a broken bone in the meantime.

And do the same for anyone else you know who is late. No second chances.

Good luck.

Even if it wasn't a party ect, it's still tell her I'd collect her earlier than I was going to x

My IL were usually at least 30mins late for everything (once 2 hours late for Christmas lunch). . Initial solution was to lie about timing eg ask them round for lunch at 12 and everyone else for 12.30 but they cottoned on to that. Second step was to start being late ourselves (which I found hard as I hate tardiness). Eg arrange to meet at a restaurant for 12 but don't turn up until 12.30pm. That infuriated my ILas I think they secretly enjoyed making a late entrance so eventually, they complained about our timekeeping!!! Thus leaving them unable to ever be late again!

Why would she change when you facilitate it.

Tell her we will meet you there at X time and we have to be gone by Y time.

She arrives late then that is on her.
You still leave at Y time, even if she has just arrived.

Boundaries are your friend.

When she sees you are serious she may tantrum, but you remain calm and stick by them.

We teach people how to treat us.

There’s your answer - let her drive herself

Exactly, people always come on threads like this complaining 'people are soooo mean, I can't help it, I'm late for everything... ' if you honestly know that you do this every time, not making any effort to adjust things is bloody rude and saying 'I won't make any effort to change things'!

Agree. Give yourself longer and use phone alarms. It is a snub to others that you aren’t trying just so you know.