Bottom line is, it's against city code. The City is not okay with it since unlicensed rentals take away from a valuable revenue source. But they don't have enough people to be proactive with enforcement.

They will enforce the unlicensed short term renal code if are complaints from neighbors. And it doesn't need to be a lot of complaints, either...one phone call to the correct person at the City and there will be an enforcement officer there ASAP. Fines start piling up fast (see this article).

As for how the places without a license "get away with it", they either have an agreement/understanding with their neighbors or their neighbors put up with it anyway and don't/won't call the City for whatever reason. They also count on the City not having enough resources to effectively police unlicensed rentals.

It sounds like you're testing the waters for renting your property on AirBnB, etc. If your neighbors are cool with it, you'll very likely get away with it for a while until the City finds a way to automatically review rental properties. But if you get one complaint and the City shows up, you'll be on their list and you'll start owing money. Depends on how lucky you feel, and how well liked you are with your neighbors.