Not a tesla owner, but AIUI you have to hold the button down on the app while it comes to you - so you'd let go if it looked like it was going in the water.

This is exactly why having open source mapping information is so useful - if you see an issue you can go in and correct it rather than hoping an anonymous corporation will do it for you.

I guess the key here is, that Tesla knows that that OSM isn't "trustworthy"[1] and consequently treats the map information as it should be: just as the source for the routing algorithm. So it uses the maps as the basis on how to get from A to B, but the actual driving is based on the sensors, not trusting the maps. So the worst case of false mapping information would be of trapping the car in a place where it doesn't know how to get to its destination.

[1] Due to its open collaborative nature, there is an obvious risk for bad or even malicious edits submitted to OSM. On the other side, "professional" and closed mapping services can have errors too, especially they run the risk of being outdated, so shouldn't completely be trusted either. Due to the community efforts, overally the OSM data should be better maintained and errors can be fixed resulting in better map quality. But the big thing is, that you cannot trust any map data 100% - and if only it has been invalidated by a tree falling onto the road.

It seems they use OSM as guidance about the structure and layout of the parking areas and then still rely on the environmental awareness of the vehicle to actually navigate.

Is the Tesla system prone to driving into water?

I'm guessing OSM is only used for routing not for actual navigation and that they filter out clear vandalism using edit criterias and ingestion delays.

The water ways are also maped on OpenStreetMap and this kind of errors can be validated using querys. Also there is a big comunity checking the changes.

That of the thousands of engineers at Tesla, who focus on problems like these full time, would never consider byzantine failures?