I am missing the "Obligation" that the crown has to liberty.
It's called nobles oblige and is the singular requirement for granting liberty to others in all forms of government. People can argue all they want about its lack of utility, but history shows it works, and the alternative is "zero obligation." So even if it doesn't work well, it's better than nothing.
@Carnival-Boy H1B is the standard work visa for foreign professionals. It is the only visa that is normally involved with IT work.
If you, as a UK IT pro, was to request a position in the US and lacked a path to citizenship (married a local, had some claim, etc.) you would require an H1B to legally work here. You specifically would be a good example of an H1B candidate.