'Scare quotes' is not the only use of the double quote.

In this case it seems that the author is pointing out that the incumbents do not in fact have any inferred or conferred ownership of these public spaces.

I think that is the most likely interpretation, but it doesn't seem like a reasonable interpretation of what was said literally in context. From a local v. foreigner perspective the roads are literally their roads. Locals do have an inferred and conferred ownership of public spaces in their capacity as the public. The foreigners don't own the streets, the streets are commons property to the locals.

I decided to treat it as a minor typo and read it as 'people would be able to ignore and excuse the increased prevalence of "foreigners" on their streets' instead. Ie, the foreigners aren't really foreigners, just citizens of non-aboriginal ethnicity.

The public spaces of a state belong collectively to the citizens of that state. The state government only administers them. That's essentially what statehood means.

By putting the word their in quotes the poster is implying the unstated assumption that states aren't legitimate.