In my state (Idaho) it’s because a good number of the legislators are landlords.

They don’t give a fuck that half their apartments are Airbnbs, they prefer it that way.

Because when a significant proportion of the housing market gets turned into business spaces (which is what AirBnBs are), it reduces supply in the housing market, pushing house prices up.

This benefits politicians in several ways:

• Most national politicians are at the wealth level were they have enough savings, excess income or simply receive “housing subsidies” as part of their work (for example, parliamentarieans when they’re from a city other than where the parliament is located) that they are also “realestate investors” alongside their day-job as politiciasn, in which case higher house prices directly make their properties worth more hence make them richer.
• Realestate inflation is generally not counted in the Official Inflation indexes in most of the West. It is however counted in the Real GDP numbers (via a mechanism called Inputted Rent). Give the way Official GDP (which is the Nominal one, i.e. after inflation has been removed) is calculated, housing inflation by feeding into Real GDP but not into the inflation index used to calculate Nominal GDP from it, directly pushes up the Official GDP numbers, so for government politicias housing inflation is a wonderful way to create fake GDP Growth (fake because house prices going up by mere price inflation isn’t really actual wealth - i.e. the “Product” in GDP - being created) which they then parade all over the Press as being the result of their great work in government.
• It makes their very wealthy and very thankful friends even more wealthy and they’ll be very thankful to those politicians. Lot’s of thankfulness available from the Owner class for people who pass measures to make their Assets worth even more, from being welcome to the most luxurious events all the way to millionaire payouts in the Speech Giving Circuit, Non-Executive Board memberships and gold-plated “Consultancy” gigs.

Quite a few cities have worked hard on outlawing Airbnb. At least in Europe and (AFAIK) Canada.

The US? I have no idea

That’s not as surprising as you may think. Take campaign financial reform. Campaign finance reform is one of the only issues that 100% of Congress agrees that it needs to be fixed. Every single one of them HATES the fact that they have to spend upwards of 75% of their time in Congress on the phone calling rich donors. There have been multiple common sense bills that have been introduced that call for capped and federally supplied campaign funds. Almost none of them will vote for it, because that removes the primary tool of power that big moneyed interests have to put pressure on politicians, so their big money donors tell them not to vote in their own self interests, and dangle a check in front of them to do so.

Lol because most of them own a few of these

I do see one problem with this type of regulation – if you say “no more than 3 homes per entity”, the “homes 4 rent” megalandlords will just create thousands of “homes 4 rent asdf” shell companies to get around the limit. I foresee tons of cat-and-mouse accounting shenanigans trying to dodge this sort of requirement.

A simpler method would be to increase both the property taxes and the homestead exemption, tuned so that individual homeowner pays about the same.

Limiting Airbnbs would help, too. Require city or county licensing for all guest accommodations, maybe, and have a set number of licenses?

Also, I don’t want to try to kill off all housing rentals. Think about college housing, about people moving halfway across the country for a job, people who’ve just gotten divorced… there are lots of circumstances where it makes more sense to rent for a time than to pony up $$$ to buy a house or a condo. In a functional market, this would be, say, 10% of housing, and you wouldn’t have the absurdity of “I pay $3000 in rent because the bank doesn’t think I’ll pay a $2000 mortgage”.