Selling your property involves paying a 5% cut to the agent, buying a property involves paying 5% in fees as points, closing costs, inspections, legal fees, etc. I would hate to do that every year or two as I moved between employers, but being able to rent an apartment anywhere in the world means I can go where there is demand for my skills.

The reason why people spend 65% of their after-tax income on rent is because people are willing to spend 65% of their after-tax income on rent. Supply and demand is a bitch, and when you fuck with it, you create massive distortions that end up enriching a small minority at the expense of everyone else (for an example, see anyone paying $600/mo for a nice 2 bedroom rent-controlled apartment in Manhattan).

And I like the idea behind a progressive property tax, but it would never, ever, ever become law in the US. Not while there is a single breath of life in any lobbyist or congressman.