I really don't understand how this is any different from regular trading. I've been able to pay people by the hour for jobs for a long time. I've been able to find small flatshares (for short periods too) in the past.

AirBNB are different, but the way I think that they're different is not what most people think. The thing they solved which was a real problem was insurance. Sure, there's a site for booking, some scheduling and payment transfer but they're not really key. It's the fact I can go to someone's house and say "Someone has checked my identity and here's a guarantee that if I break/steal things you'll get reimbursed" that smooths over the risks.

Uber, in the UK, is virtually identical to other taxi firms.

AirBnB, Uber, Lyft, etc. are all using assets that were not intended for paid services, whereas the people you are paying for services are using assets that have such intention.

The shared economy is (or was) more about accessing assets that were locked up by personal use, but still being underutilized. From an ethical perspective, it's maximizing value from something that wasn't easily accessible before.