I think the gig economy should have a similar Pedlar's License. There should be some paperwork. Maybe no more hard than Basic Food Hygiene that you get working in the food trade.
This would also allow local authorities to refuse. So if they didn't want the food delivery guys then they could just restrict licences.
Standards, e.g. lights on bikes, MOST for cars, all should be part of this license for doing door to door deliveries.
Standardisation could result in no drivers getting it wrong whether hired the UPS or FedEx way.
If the driver ID was a standardized way of doing tracking then that could even be part of the final mile procedure.
If we had rules about what a license should promote (such as public safety, accountability, etc) and what it should try to prevent (rent seeking, protectionism) and metrics by which to measure this (even if an impartial panel), we could possible greatly increase the number of licenses we require while also lowering the bar of entry for many existing licensed businesses.
I understand this would be a tricky path to take. It's layering bureaucracy, which is often problematic. But I'm not sure we necessarily want random unaccountable people driving around throwing packages at us, nor doctors practicing without experience, and I don't think having to pay $1000 and take a one week course for licensure to deliver packages for Amazon is useful either.
1: http://www.npr.org/sections/money/2017/04/14/524007928/episo...