Not wanting to change a tyre is fine. I don't change mines.
Not knowing how to if you were stuck in an emergency situation is just plain daft. It's nothing like not knowing about how your shoes are made - that is a really really stupid thing to say. With a car you are responsible for a tonne of heavy machinery which can take you anywhere.
Ok, scenario - you are in the country, on a back road, and you have a puncture. You pull over and there is no mobile signal. No houses are in sight, it's getting dark and the road is very quiet.
Wwyd then????
And yes posting things that suggest women are less likely to know basic vehicle maintenance IS letting the side down. It's not some big huge girly in joke about how vacant we are.
I would make exactly the same sort of response to man posting a stereotypical comment about not knowing how to use Thr washing machine.
And also as op has amply demonstrated, it leaves you extremely vulnerable to being ripped off. Fifty quid for expanding foam indeed!
(op, it doesn't have to be Asda btw, eBay, most supermarkets, halfords even should have it for less than a tenner and they are MASSIVE rip off merchants)