ls it me? Yes
Or is it cheeky and bad mannered? Also Yes.
I can't see a moment in your entire initial post where you have spoken to your friend about this - you seem to just put up with it:
On one occasion last year, we arranged to go to meet another friend of mine for about an hour (for a specific reason) before she (other friend) went to work. When l arrived at my friends to collect her, she'd only just started putting her makeup on. (Which takes forever. At least an hour). She sat there, painstakingly putting her face on, no hurry, no sense of urgency whatsoever.
You already knew she takes an hour to put her make up on.
That was the time to say "look, you're not ready, AGAIN, I am not prepared to be late or miss seeing Other Friend, I'll see you next time" - & left.
The result being that by the time she got ready, we didn't leave her house until after the time we'd actually agreed to meet my other friend.
Until you take responsibility for your part in allowing your friend to keep showing you how much more important her time is than yours, she is always going to be late.
You are an adult - who MADE you stay in Tardy Friend's house, who stopped you from leaving to meet Other Friend?
It is your own fault you missed Other Friend - you did not leave Tardy Friend's house in time. You can blame her for her own lateness - you cannot blame her for yours.
Twenty miles away. By the time we were halfway there, my other friend had to leave for work.
You already knew how much time Other Friend had available.
What possessed you to carry on regardless?
Had you phoned her from Tardy Friend's house, did you phone her on the way?
So l wasted god knows how much time, and forty miles worth of petrol for nothing.
But my point is - why did you?
You know Tardy is a useless timekeeper.
You knew when you arrived at Tardy's that she was going to blithely apply make up for an hour without reference to anyone else's schedule.
You presumably were not held at gunpoint, but decided to await Tardy's pleasure instead of being sensible & leaving her to it.
Even if for some as yet undisclosed reason you were unable to leave Tardy's house without her, why did you not ring ahead to postpone meeting Other - what on earth was the point of driving there when you knew she'd be gone before you arrived?
What did you say to Tardy about it? Or were you BOTH acting surprised that other people actually stick to their time promises?
You are not going to change Tardy's behaviour - she clearly has issues & no qualms about acting them out no matter the inconvenience to you.
So you need to change YOUR behaviour.
Tell her clearly & calmly "I will be picking you up at 10, if you are not ready I will be going on without you."
If you are meeting at the cinema "OK show starts at 7.15, meet you there at 7.10, if you are not there, I'm going in without you."
You need to mean it, you need to stick to it, & you need to do it.
Your biggest problem is you allow her to get away with it.
Why, I can't imagine - she clearly has no respect for you.
What did Other Friend think about you blowing out the meet up with her? Because in effect, that is what you did. How do you think she feels about that? You also made her time less important than Tardy Friend's, & showed her that Tardy is more important than she is. That's not fair or kind is it?
You can continue blaming Tardy for it & feeling pissed off - but that won't change a single thing.
What weird voodoo has Tardy cast on you to make you believe that you have to hang on for her like this?
The only way to change it is to take responsibility for yourself & stop believing that Tardy has the power to make you late, or miss events & meet ups.
You don't deserve to be treated like this, & imagine how your self esteem will improve when you start refusing to be.