As a US ex-pat living a long time in Austria, I'm familiar with both systems. It is a pretty damn simple problem to fix...on paper. The problem in the US is political corruption that then affects the tax system.

In Austria, foriegners (like me) have to go through a legal process to justify why we need to own more than one property. This alone cuts down on speculation.

Taxes on property are paid up front in Austria. This makes "flipping" (i.e. speculation) much less attractive.

Most importantly, high marginal tax rates make it harder for even high earners (like myself) to save cash for multiple properties. It is great when most people can own their own home. It is not great when a sliver of people own 3000 homes while the vast majority can't afford their own.