There are a couple of things here.
Whenever you get new colleagues on a project, they need to load tons of information in their head in order to become productive. That's just how it is. Nobody hits the ground running. They need to learn the project, the business, the rules, the procedures, policies, etc. You can't work on something you don't understand and expect a successful outcome. This is true for any project, no matter if it's within a Scrum team or not.
So the first thing is that the new people need to be willing to learn. They must put in the effort to learn. Speaking strictly of Scrum, they must of course learn what Scrum is all about, read the guide, read books, make an effort to understand what all the events and artifacts are for, etc. Scrum teams are self-organizing, so everyone must figure out how to do their job. And if they need to learn something to do it, then they learn it.
But the second thing to point out, is that Scrum is all about teams. In a team, you have communication, interaction, collaboration. New colleagues get integrated into the team from the beginning. They are not alone, or by themselves. The team needs to support and help them to become productive. And this is where what you said worries me:
[...] nobody is there to drill them; they have to find everything out by themselves.
Why is that? Do you lock people in a room until they load the information in their heads on their own and only then let them out and put them to work? It doesn't work like that. Not in Scrum, and not anywhere else. When new people join a team, the team changes to include them. Their work adapts to meet this change. The Scrum Master might need to hold trainings, the new colleagues might pair with someone else, they might slowly start contributing things to the project while they get the hang of things, the team velocity might change as the team takes less work in the sprint because they need to offer support for the new colleagues, etc, but eventually people get the hang of things and the team finds a new cadence as they work together in the new team format.