Earlier this month, roughly 37,000 drivers for Uber and Lyft were mailed letters from San Francisco City Treasurer Jose Cisneros indicating that, as contractors, they must apply for business licenses to operate within city limits. Those licenses go for $91 each, but might possibly be more expensive than that with additional fees of $155 and back penalties for every year operated without a license.

While the number of Lyft and Uber drivers who do register will likely be far fewer than 37,000, the revenue could still be significant. And it follows a pattern: The Treasurer's Office tells SFist that Airbnb users, who must already register with the city in what many describe as a Byzantine process, were mailed a similar order to additionally seek business licenses some time ago.

For example, a letter from the Office of Short Term Rentals forwarded to the Glen Park Association explains that business registration is also a requisite for short-term rental owners like those who rent through Airbnb and VRBO et al.

"You first must obtain a San Francisco Business Registration from the Office of the Treasurer & Tax Collector," the letter reads, one item on a long list of requirements.

The registration process and tensions surrounding it aren't getting any easier. San Francisco's Assessor-Recorder recently (absurdly) insisted that hosts itemize and pay taxes on their every household item and stick of furniture that a guest might conceivably use.

Concurrently, Airbnb is increasing its financial presence in its host city of San Francisco. According to 48 Hills, the Committee to Expand the Middle Class, which is set up by the company, has injected $245,000 into local politics.

As Supervisor Wiener checks up on the Short Term Rentals office and Supervisor Campos proposes a law to directly fine Airbnb for any illegal, unregistered listings it allows on its site, the company can literally afford a few more allies in local government.

The causes they're supporting: $100,000 to Prop A, $100,000 (Lee's $350 bond for safety and homelessness) to Prop B (Farrell's $3 million for parks and recreation from the general fund), and $10,000 to Prop D (Malia Cohen's police accountability initiative). The Committee is also dropping $20,000 on the Democratic County Central Committee.

In a statement to Re/code, an Airbnb representative wrote that "This is one part of our growing effort to stand with those who fight for the middle class in San Francisco."

Related: Campos Proposes Law To Fine Airbnb Directly For Unregistered SF Listings
SF's 37,000 Lyft and Uber Drivers Will Be Ordered To Get Business Licenses