Why cannot immigrants SELF-apply for a legal visa to work in the U.S.A.?

Well, it is the law. See the INA.

The law only set forth a few ways in which an alien can self-petition for a green card:

1.The diversity visa: 50,000 available to a few countries, not Mexico.

2.Employment Visa: 34,000 for people with extraordinary abilities (usually a Ph.D. and publications and prizes.)

3.Investor Visa: 10,000 for people who invest at least $500,000 in a poor area, or $1,000,000 in a rich area.

4.Violence Against Women Visa: For people who have been abused by U.S. Citizen spouses

5.U Visas: 10,000 for victims of serious crime (Rape, attempted murder, etc)

6.Asylum: For people who will be persecuted on account of race, religion, gender, political view, or social class if they return to their home country.

You can self apply if you are very rich and want to invest or you are an award winning artist or scientist or doctor that is world renown.

It is a simple matter of whether you are wanted here by someone. If there is no one asking that you come, like a family member, an employer, or the country as a whole because you are so rich or so great, then there is no reason to let you in.

Oh, I forgot, as the poster below points out, you can also come on your own if you are a victim, which is just as good as being rich or extremely talented.

why dont you explain how can a self applicant get a visa if he has NO Money or Support. Who's gonna support this "self-apply" person if there is no one to be held accountable should things go awry???

you won't be able to be interviewed on the U. S. Embassy in the united kingdom as your visa is expired and you're actually not from now on seen a criminal uk resident. you are able to in basic terms be interviewed on the U. S. Embassy on your united states of america of criminal place of abode, which ability you're able to decide to return on your homestead united states of america first and be interviewed on the U. S. Embassy there