It _could_ introduce more barriers to reduce scammers, but that would come at a cost to both buyer and seller UX.
There is value in simplicity, and the market thus far agrees.
Craigslist is the anti-thesis to the hubris-fueled notion that technology can and should solve every problem, including dishonesty. I've not yet been scammed on Craigslist because I've built up a valuable skill in identifying scammers in general rather than relying on an imperfect system implemented differently on all marketplaces. In return, I do not get scammed as a _seller_, which is something most marketplaces seem to neglect.
More broadly, we often blame human nature on software implementations, as if there was a software solution to (all of) such without trade-offs.
When I log into a “modern” app today there’s almost always a new feature in my face or an old feature moved to a new location (or simply deprecated)
This is precisely because they're the kinds of transactions that most people would never even consider to take part in without first being able to establish a certain level of trust in the other party.
I think this is probably the biggest competitive advantage for AirBnB against challengers in the space. Bootstrapping a 2-sided marketplace is hard enough to begin with, but doing so while building up a network of trust among users so they can comfortably partake in transactions with a high trust-barrier is even harder.
The perception of safety could be more dangerous for some using air bnb as opposed to those on CL who are fully aware that there is no safety net nor hand-holding.
AirBnB handholds the traveller from the moment they start looking to when they're going on the trip. CL just presents an ad, and lets the parties email/text on their own. AirBnB handles the financial transactions, with all that that entails, and CL does not. AirBnB facilitates the communication between the landlord and the customer. They also let you add on "experiences" as part of your trip. They also include an identity verification system for both landlords and consumers, and there's a review/rating system for both. It might not be perfect, but Craigslist has nothing like it. For example, I generally avoid renting places that don't have reviews, and landlords can choose to ignore/reject renters who have built up a bad reputation.
CL, on the other hand, has a reputation for being full of scammers and other shady people.