Most vendors make it difficult for their customers to just query these databases. There is some genuine technical good reason for that. The economics of many vendors selling cloud applications for instance is that they need to be able to control costs - they use quite a small amount of hardware resources per customer which would become larger if customers started to heavily access the data in these systems.
There are also business reasons - a lot of vendors want to upsell their customers on the ‘gold package’ with extra functionality that is integrated into the system.
So in practice most vendors put limits around how easily their customers can access their own data from the vendor system.