Deportation doesn't come into this, that's only relevant once you've broken the law or overstayed your visa.
The game is about meeting criteria for a visa route, and doing seasonal work does not help in any way. Having a UK degree enables you to get a job here easier, but thats about it.
In UK, if you are switching from a short-term to long-term visa you have to leave the country and apply for a visa again from outside the country.
Even if you are applying from inside the country, the home office does not hesitate to reject applications for the tiniest reasons. Once that happens, some people might go to court if they have the money and ground to dispute the decision, if your lot in your home country is really bad you might stay illegally, but for the vast majority neither option is worth it and they move on.
Whether you are pro or against immigration, it's unclear why unscurpulous employer should be the ones to benefit from this arrangement
Yes, that is precisely the route.
The billions (like moi) in the third world have realised that the longer they violate the immigration laws, the better their chances of having some activist argue their right to stay.
Their is no other law/regulation that I know of where the longer you violate the law, the more rights your have.
Which is exactly why the boat arrivals to Australia dried up once the processing was moved outside the jurisdiction of Australian law.
They were on to us.
I suggest you research “adverse possession”, and “easement by prescription”; if you view nation-states and their territory as analogous to persons and their real property, they are quite similar concepts to what you seem to view as unique.
They all know that once they are inside the borders, its harder for the authorities to deport them.
Its basically the price to pay for a shot at first world lifestyle.
The last thing most of them want is a crackdown.