For small purchases, payments are usually in advance. Especially if it is a rather custom build.
Larger purchases may have an up front deposit. But as the EV manufacturers are learning, they got many more deposits than actual purchases. At the same time, buyers are finding the price for the reserved vehicle was just a fantasy.
I have no problem with the concept of an up front price for an item entering the stream of custom builds.
What I'm reading is the problem that buyers paid for the attachments, and never received the product. A quite a different issue.