Most cities have a law in their zoning code that prohibits rental periods of less than 30 days.
That doesn't apply to guests, since a guest has no rental agreement.
To me, it's a classic economic issue, the full utilization of assets. When there is a vacancy of any sort, it's not good for anyone.
This new technology makes it easy to eliminate these vacancies.
Enforcing the zoning laws will not eliminate illegal short term rentals (STRs). It's very similar to the prohibition of alcohol. When there is strong demand, supply will be created, legal or not.
Commercial and larger operators of STRs will be happy to pay the hotel tax. For occasional landlords, it's not worth the hassle. They will avoid licensing and taxation, so don't bother.
Deal with complaints as they arise, because there aren't many. Short term tenants can enter a building very quietly if they are required to. Once they are inside, they are likely to be just as quiet as any other tenant.
Summit County, Colorado (birthplace of VRBO) is a good place to study the issues. 75% of the housing stock is not occupied by permanent residents. The internet handles a large and growing percentage of STRs, and no hotel tax is paid. Hotels are not complaining. Permanent residents are not complaining.
The efficient utilization of these assets can prevent the construction of large hotels, which are even more inefficient in the off season, and provide a less interesting and more expensive experience for the traveler.
As Azita said, STRs are likely to have better maintenance inside and out.