My biggest take away from this is not really anything about the specific security vulnerability, but rather that real estate industry people will buy any SaaS product without research or any due diligence.

I have personally seen real estate people buy some trendy new app based intercom or entry phone system and jam it onto the front of their building and try to require that all of the residents use it...

What would you expect them to do? They're in real estate. They're not coders. Sure, they could hire a company to evaluate choices and let them know, but they're so not coders how would they even know that's something that can be done? Also, how much time would that add to getting off of a spreadsheet that gets emailed to people each time it's updated?

We seem to lose the concept that people outside of tech have not idea about anything other than whatever they do. Just because you (the royal you) knows the ins/outs of security software does not mean the other 98% of the population does. Yet you're blaming them for buying a tool to do the thing they need help. Blame the devs for being idiots. Don't blame the users.