You have part of the equation right, the part about supply and demand and the welfare state.
There are two parts to a free market and supply and demand where labor is concerned. You have to pay enough to get a qualified person to accept the job you are offering. For it to be enough the pay has to be attractive in relation to other alternatives, like the welfare state you mentioned and the type of work to be done.
Many of us would bus tables, dig ditches, etc., for $75,000/yr., but who could afford to eat in a restaurant that pays bus boys that much or buy a house from a builder that paid a ditch digger that much? That is the other side of the "if it paid enough equation". You forget how those wages affect you, the consumer.
The thing that must be recognized and fought is that we are right where the left has planned for us to be. They have been stealthily working on this for almost 100 years and the payoff is almost here for them.
They have infiltrated our schools, the unions have always been controlled by the left, the trial lawyers, the Democrat Party has become the Communist Party, our immigration policy, our government regulation and our courts, all the end result of a long time effort by the left to take over this country.
Their strategy has always been to divide and conquer. They set rich against poor, black against white, male against female, straight against homo, parents against children and teachers, immigrants against citizens, workers against management, Democrats against Republicans and America, and now they are succeeding in setting conservatives against conservatives.
Some of us had better wake up and see past our noses.
They wouldn't have to pay $75,000 a year. Just a competitive wage for the market. I don't believe the choices are $75,000 a year or illegal labor. Yes, we as consumers might absorb additional costs in goods and services, but only to the extent that the market would allow. It would also be partially offset by the increased tax base. Also, for every worker that moves off of government assistance to a paying job, the effect is compounded.