In France, they do. If someone shows up and offers the advertised price, the deal is sealed as well. Even for $5m that you don’t have.

If they offer a lower price with conditions and the owner says yes, it is also binding. It can be on a simple free paper, and going through a notary is optional, even if recommended. The only exception is that the purchaser has 10 days of legal withdrawal after signing the contract (only €300 notary costs). The seller can’t withdraw, unless conditions were manually specified. I wasn’t aware of that when I made an offer by email, fortunately the landlord explained me that I should list the exceptions/conditions in my own interest…