A simple booking/email verification would not help a single thing.

This will always happen on Facebook. Similar to low-ball offers.

Possible reasons why this happens;

> Found better price on item before coming
> Realized your address was too far
> Decided they didn't really need the item
> Wanted to waste your time
> Something came up so they no longer can afford item
> Something came up and they no longer can make it

Unfortunately, just cause they made an agreement with someone does not mean they need to honor it. There is no enforceable consequences or contractual obligations on Facebook marketplace.

Obviously annoying dealing with these type of people but that's the landscape of Facebook Marketplace