It doesn't matter if someone can build a career out of seasonal jobs, which is entirely false btw. The market will dictate how much seasonal goods and services are worth, thus setting wages and property values.
Just like farm labor: without importing foreigners, legal or otherwise, wages would go up, food prices would go up, prices, wages, and property values would normalize to market rates.
your libertarian view of economy is too naiive. There is no "free market" in the US. Everything that impacts inflation/CPI is tightly controlled by the federal government with monetary tools like credit expansion, rates, federal incentives and such.
the reason why America wants to suppress low value jobs, is because they are input to the actual output of American economy: agriculture, high value industrial goods, tech services, financial services, real estate, financial asset s and services.
These are the actual components of US GDP and American government does everything possible to keep the input to these sectors stable/low, in order to protect the profits of these industries.
Do you see how wages seasonal workers are lower priority to the profits of Vail Corporation?