> [...] economic models should always be critically approached from the perspective of the exploited.

Why? Also, who's getting exploited here?

When it comes to Airbnb - neighbours who now live next to a hotel room, communities that are now full of transitory people and tourists rather than stable long term residents, landlords who had no-subletting clauses in their contracts.

That last one is the thing that makes me most surprised that Airbnb has so many libertarian supporters. It's the biggest attack on basic property rights and contracts in quite a while. Personally I don't have much sympathy for landlords, but I do think that if we are going to regulate to no longer allow such clauses in contracts it has to be applied universally, not just for people using Airbnb.

Uber drivers are potentially getting exploited because they don't get the protections of regular worker.

You could say that they could just go over to another service, but there are only so many of these new-age taxi operators. Unless the number of drivers is extremely limited, the same thing will happen to them as to people in other industries (say, cleaning houses):

The customer wants lower prices, the business wants higher margins, so the business squeezes the (badly-positioned) workers.

There's already been protestation with Uber's "misleading" ( it was heavily subsidised at first, but stopped recently) wages given to the drivers.

This is just another example of why the labor market is really not an efficient free market.

Thanks. How high is the barrier to market exit for Uber drivers?

well, if you've been a taxi driver for a while, pretty high I imagine. You might have other marketable skills, but you might not.