They increase the prices and they could surely pay more than the Israeli residents: these taxes could be reverse in a fund to help them to access to buy less than the market. The non resident owners could so help directly those that cannot reach too high prices. And they make a big misvah!
Firebomb thrown during demonstration in northern Israeli town of Umm al Fahm (Haaretz)
from the article: Netanyahu cancels Poland visit as housing protests take Israel by storm