Kraken, you were asking about visas.
Citizens of most EC countries, including the UK, who have a right of abode, have a concession that allows them temporary entry to the US, for up to 90 days, without needing a visa, provided that they are coming for a holiday or on business. They are not allowed to convert that temporary concession. If they want to seek work they have to go home and apply for a visa and work permit.
You may possibly be surprised to know that US work permits and visas are not handed out like confetti.
A person who wants to enter the US for education or to seek employment has a very, very, very much harder time of it. You may be aware that to the South of your country is a substantial border fence to keep out such people.
When Hugh Grant is offered a part in Hollywood, his application for entry will be sponsored by a US employer who undertakes that he has a firm job offer for Hugh, and that it is for a job which no US citizen can do, and the sponsor guarantees that Hugh will not become a charge on the public purse by being destitute, sick or unemployed, or try to take jobs from other Americans. The sponsor has to bear the cost or supporting Hugh or sending him home if it all goes wrong.
Do you know anybody who will do that for hundreds of untrained, inexperienced, starry-eyed foreign teens who have been given the impression that shovelling thousands of dollars into the pockets of an exploitative company will lead to Hollywood and stardom?