People talk past one another on this issue and use terms in colloquial ways.
I walked through a beautiful housing development the other day in a very posh area of London that I could never in a million years afford despite having a HHI of £250k+. Clean, safe, amazing facilities, private gated gardens etc.
It was the middle of a weekday and I saw a woman, maybe Somali? in a hijab, carrying in Aldi bags and talking to her son? aged in his 20s/30s? who was sitting on the steps.
Now maybe this woman's husband was a hedge fund manager and they paid for that house with his bonuses but let's be honest, it was a new development and this was almost certainly a social housing case.
I don't know anything about their situation. They could be recent refugees, immigrants from a few years ago, heck they could be second generation and born here. But either way my taxes are going to give them this life which is way beyond charity and is a luxury I can't afford for me and my children, and the only reason their family is in the country at all is because of immigration from at some point in the last 10/20/50 years.
Now I don't post on Facebook. I'm an immigrant myself, on a skilled worker visa. But how is it hard to understand that it's not a myth that a lot of resources DO go to support immigrants, and that the UK's current system is very bad at selecting for immigrants who will be self-supporting, and that people can use the evidence of their own eyes to see it?
Sophistry about definitions of "illegals" is irrelevant when the question isn't "are these people technically here via a legal route" but "should that route exist?"