To think you can’t actually get car seat advice from anywhere?

Ive not had to use a car seat for many a year but always felt the same.
A relative used to work for Mothercare and was trained in car seat performance and fitting etc and would also ensure parents/carers knew how to fit and use properly before leaving the carpark.
All car seats have to meet a minimum standard but a few companies used to go well above the the expected standards ie crash impact at more speeds than required etc. I dont know what this is like now.

Would safety charities or Which, msybe give recommendations ?

How much advice on one fairly trivial aspect of parenting do you need? As long as you are using an age/height/weight appropriate, properly fitted restraint in accordance with the instructions then you’re doing fine. If you want to maximise safety then rear face. There’s advice on the legalities online on .gov website. There’s advice from retailers on what product does what and manufacturers instructions on what seats do what, how to fit them and what cars they fit in. There’s online advice where people will tell you the safest thing is to RF, because it is. And then you filter all that, decide your priorities and what works for you, ensure you are acting in accordance with law and then don’t get drawn into ridiculous online debates.

People who REALLY CARE about other people making the wrong parenting choices.

As a basic, the seat will be legally compliant and this country has a higher H&S threshold than many. I’m sure you can always be that bit safer but sometimes you have to weigh it up with what’s realistic or whether a child constantly screaming because they can’t cope with being rear facing is more of a distraction for the driver and dangerous.

What kind of person identifies as an “online car seat mama”?

You can't engage with FB car seat groups - they are very extreme. I couldn't get over the fact they think the that kids should miss school trips rather than travel on a coach without a car seat. I say this as someone who has used ERF seats for a small 8 year old and keeps using HBBs past 135cms. But I also think it's fine for you to put your 5 year old in that (good) HBB especially when you see people who use no seat or badly fitted seats all the time. The crazy groups should stop scaring caring parents who have enquired how to keep their kids safe away and focus on increasing correct fitting and use of car seats with advice on best brands and mention ERF is safer but understand there are plenty of reasons it wouldn't be practical after toddler years.

I also feel like I can’t get good advice!

We don’t have a car but have a car seat for use in other people’s cars and rentals. I’m always so worried it’s not fitted correctly or I haven’t done the straps right. Especially as we only use it about once a month! I wish there was something like going for an MOT at a garage where you could get a lesson.

Ours is a Silver Cross and all their online videos are wordless.

Online car seat mamas are nuts. Ignore, your car seat is fine.

I suspect you know full well that this is a contentious subject and starting this thread is deliberately provocative.

Like so many parenting decisions, make the one that’s right for you and your family and leave it at that.

They are bonkers.