Because then we'd effectively have open doors
And that would never go down well
It appears the doors are open; half a million people per year, yet only a small minority are illegal. ~That's what she said. I assume it's probably much harder for some people from outside the UK to enter, those people who aren't seeking asylum. Is there a common factor among the majority of the illegals? Why don't those few fill the criteria? I can't see any reason for anyone to be there illegally, unless they're criminals or possibly lazy about the rules followed to be there legally.
I can't find the exact rules, and TBH, I dont really know the rules myself. They are something like this though:
All members of the European Economic Area can move freely within Europe. That means that many Eastern Europeans can freely enter Britain. Some people are annoyed that people from poor countries like Bulgaria can freely move to Britain.
Most people from outwith Europe must apply for a visa. I think there are different types of visa. Some types only allow you to stay a short time, and not allow you to work or claim benefits. Others allow you to stay long-term, and to work and claim benefits.
Its easy to get a visitors visa, that allows you to come to Britain for a short time. Many people come on a visitors visa, and just never leave, often working illegally. Its harder to get a long-term visa that allows you to work. If you come from a poor country with no ties to Britain, and you have no skills that are seen as valuable to Britain, you dont have too much chance of getting a long-term visa.
If you dont get a visa, then the other option is to apply for asylum. That is only granted to people who are at "risk of persecution" in their homeland. It seems that different people have different interpretations of that.
Another issue is that asylum seekers have to apply for asylum in the first "safe" country they enter. Someone could be denied asylum because they enter Britain, via France. If France is the first country that they arrive in, then the law says that they must apply for asylum in France. Many asylum seekers attempt to choose what country they gain asylum in.
Basically, many illegal immigrants are people who enter the country on short-term visas, and dont leave when the visa expires. Some illegal immigrants are people who applied for asylum and were refused, and they have chosen not to move on, but just stay here illegally.
I've probably missed some stuff out, and some of it might not be fully accurate. It seems surprisingly hard to find out the exact rules.