Well for one thing, a lot of them sell SIM kits and collect money from you at the point of purchase.
In a lot of cases, they include a certain amount of credit so when you purchase a SIM for 10 Euros, it might have 5 or 10 Euros of credit to activate.
But it's a guaranteed way to book revenues on a sale.
In any event, I looked at the eSIM on my iPad Pro. Only a handful of options in different countries and the cost way way more than I would pay if I just go buy a SIM and activate a data bundle directly.
So I've never used the eSIM, just popped in a physical nano SIM.