One of the key differences is public vs. private. These are requirements from the government (town, city, municipality, county) and should reflect the will of the people. People have more rights on a public level and fairly assume that people should be able to transact without much scrutiny. Drivers want to make extra money, riders what transparent, available cheap transportation. A small number of rent-collectors are worse off in this arrangement, but broadly both sides of the market reap reward.

In the above case, Twitter is a private company, and has a right to do whatever it wants with it's service. It can get away with as much as it's users will tolerate. As a public company it has shareholder requirements, sure, but in this case it was a technology/UX problem. Meerkat was doing something that most seem to think devalued peoples user experience, and abused the purposes of implemented features. Meerkat gained a lot of exposure, and I am sure some people did benefit by it, but by and large the beneficiary was Meerkat gaining exposure by broadcasting pre-made content (spamming).