The design justification for the four buttons is twofold:
1. It is a very active hazard. It is something the player can mess up really easily and tells them that it is something that they really need to do right. It makes it very clear what the penalty doohickeys do
2. it is the most obvious indication that things on panels can be clickable. It's buttons that are designed to be very inviting to click! It teaches the player that you can click on panels as well, unlike the snail.
So that's the reason we put in the four buttons so early ^-^. It doesnt show up for a while again after because it is quite demanding, but exactly for that reason makes it a really good doohickey to interact with early to set expectations.