MS Access is a higher barrier of entry to a developer who knows some other language but not SQL and just wants to throw on a datastore than MongoDB is.
It might be a lower barrier to entry to learn Access from the beginning than (programming language) + (MongoDB) -- though I'm somewhat dubious of even that.
Since the newer versions of Access use SQL Server Express as a backend, I would expect them to be significantly more reliable and performant than MongoDB.
MS Access is a higher barrier of entry to a developer who knows some other language but not SQL and just wants to throw on a datastore than MongoDB is.
It might be a lower barrier to entry to learn Access from the beginning than (programming language) + (MongoDB) -- though I'm somewhat dubious of even that.