No, I just assume that a database has a similar set of features as other databases have had for decades. Mongo does not; it is clearly the exception - and for possibly nefarious reasons, as well.
Any time I deploy something as critical as a database, I carefully read about what it does and how it works. Not doing so is like signing a contract without reading it.
I don't understand this reasoning. We are talking about defaults. Defaults are used by people who did not tweak the settings yet. If I am just starting building a thing, I will have bugs and squeaks and I want to make sure I am not fooled by some unreliable data store. I am not likely to need 100GiB/s throughput, but I am very likely to have to hunt bugs, like "I did click on this <like> button but it did not add to the total likes". And I would really really hate it if after half a day of bug hunting I would realize that my data store just didn't store the thing...
These are systems designed for the real world, where people don't read the manual until they have to.
When people assume MongoDB was similarly designed with their best interests in mind, that's when things go wrong.