Earlier quoted context omitted.
The economic middle road is to penalize the externality. If a community is concerned about non-resident property owners, they might consider taxing them at a higher rate and longer-term full-time residents at a lower rate. I don't know if there's anywhere that actually does this, however.
In the UK, there is no capital gains tax (CGT) on the sale of your 'principal private residence', i.e. the place where you live. So, yes, non-resident property owners are already taxed differently.
Especially as CGT is typically lower than income tax, so investors would prefer capital gains over rental profit. (And if their rentals are generating profit, might be tempted to buy more rentals that are not profitable but rising in capital value, so that their rental profit is lower but capital gains are higher).
You hear stories of investors who keep on acquiring and end up with dozens of buy-to-let properties and are leveraged up to the hilt.
Bradford & Bingley, which was the UK's buy-to-let mortgage specialist, was particularly hard hit by the GFC.