I think a lot of words get used up on the precise technical differences between legal, illegal, irregular, asylum seeking, granted, visa, ILR etc etc.
As a legal immigrant on a Skilled Worker visa (and definitely a net taxpayer, and doing my best to integrate, including marrying a British person) I do appreciate it when people try to make this distinction.
But the legal categories don't line up neatly with what people perceive on the streets. People look around the high street and react to the sight of a bunch of random foreign people who've suddenly appeared out of nowhere in large numbers in their town, milling around during the day.
"Oh, technically that person had their grant approved and anyway it's not illegal to seek asylum even if you came through an irregular route!"
"Oh, technically that person got sponsored by their cousin who works in a minimart so they're actually a skilled worker who contributes more than you, you lazy local!"
"Oh, technically that person overstayed their visa 20 years ago but they've now got ILR on the basis of long residence, it's irrelevant that they've been in and out of jail that whole time!"
There's no need to tie ourselves in these stupid knots. The problem is not any of these very broad categories, it's persistent, ongoing, low-quality immigration across all categories.