It has to be a case of outgoings rather than income that determines how well off you are.
But it doesn't, really. Because if you aren't well off, you can't rent a 3 bedroom house in the first place. Or find £50 a day childcare, or pay off £1k a month in debts (so your debts go on forever because you can only pay such a measly amount back), or spend £200 a week on food (for 3 people?). I didn't make £50 a day when I worked in the UK. 8 hours at minimum wage is £49.44. I would literally not have been able to afford to work. In fact, I wasn't able to afford to work full time. It was totally ridiculous, I did the calculations. FT wages + tax credits - childcare costs was less than no work + tax credits. Luckily for us PT wages + tax credits - (smaller) childcare costs was higher, because on the middle option we were not covering the bills. All of this was with DH working full time.
Agreed that the cost of living is shit, and I'm not for one moment saying that you shouldn't spend £200 on food or have a 3 bed house or anything at all. But these things - though they might not be changeable right now - are part of being well off. It is fortunate to be able to afford £1k on debts, to be able to live in a larger house than you need, to have a job which pays well enough to cover childcare and not be constantly dancing around stupid arbitrary hours limits, to not have to eke out food based on budget constraints. And yes, as you mentioned it, to have a car. I don't begrudge any of these things but it's not really right to claim that you are badly off when you have all of them.
TBH, though, It is exactly why we left. I still don't really believe that we did it, or how. DH got a job and moved out first and we followed on a budget Ryanair flight with two suitcases and the rest of the stuff posted in 16 boxes. Sold the furniture. We have little to no savings after a year, we are living in a tiny roof which is overpriced, we are not earning massive amounts more, probably have less actual income because of higher taxes, but it feels so much easier and less stressful. There is no worrying about how to pay the bills, an occasional eek we only have €x left for the month, but nothing serious, nothing like we did have.