Sorry to clarify. You are moved around the country continually so that it is exceedingly difficult to get in front of a judge and also speak to your lawyer. This is basically torture to most people, you are then pressured and repeatedly asked (in some cases lied to) to sign documents agreeing to be deported

The definition of being "illegal" in the eyes of the law is not actually really well defined at all. It is pretty much a vibe check

Entered via a port of entry and visa overstay? "illegal"

Entered via a port of entry and visa overstay, but now you have legal status? "Maybe you are illegal"

Entered not via a port of entry? "You are illegal"

Entered via a port of entry with legal status? "Legal but you might get detained for several days"

Entered via a port of entry with legal status but you attended a protest? "Legal but the government doesn't like you so expect to be detained"

Born and raised in the United States but don't carry your passport? "Legal but expected to be detained"

Entered via a port of entry with legal status BUT you have a traffic ticket and a bench warrant out of state "Illegal and criminal! Expect to be deported"

Might I add that only one of these above conditions is valid for deportation and a ban and every other is a violation of your rights