I find this sort of thing very frustrating to read: "The search tool is antiquated, the images are poor or nonexistent, locations of listings are hardly dependable, and you can forget about an integrated way to save anything for later reference. There is a litany of shortcomings that come with the Craigslist apartment search; they are many and they are painful..." If you don't like the site, don't like the UI, and ca…
If you don't like the site, don't like the UI, and can't stand the UX, then don't use the site. Nobody is forcing you to search for an apartment on CL. Nobody is forcing owners to list apartments on CL. Apartments aren't a fungible item. If I'm looking for an apartment in a certain area and 75% of the apartments in that area are only being listed on Craigslist, then how can I realistically "choose" to use another ave…
There is absolutely no reason that PadMapper cannot call them on the phone, and ask them to list with PadMapper. They can make it trivially easy supporting email, phone, or fax listings. They can sell them on using PadMapper.
Many apartments are owned by Real Estate Investment Trusts (REITs) there are dozens (not hundreds) of those. You can sell the REIT on the concept of easy listings that are so much better/cleaner/easier than Craigslist.
Craigslist was created when near every apartment was listed in the Classified Ads in the print newspaper. That wasn't "lock in" it was an opportunity, they sold these folks on lower costs (since Classifieds were a money fund for newspapers) Landlords hated the extortionate prices that the newspapers charged but they didn't have an alternative, Craigslist gave them that alternative, they moved.
So the 'answer' here is to actually build a classifieds business around rental space. That takes more than slinging some node.js and scraping other sites. Granted its 'easier' for a technical person to do it that way, but its not a 'sustainable' way of doing it.