the difference on the base model mercedes c class between getting a less powerful engine and the one that is one level up is like 3.5-4k eur.
that is a lot of money. if i could unlock the bigger engine with just 400 eur i would buy the base model.
manufacturers don't want that, and is one part of blocking the touching of the ecu. the other is also that the navigation and a lot of other things is just disabled in ecu, and could be easily unlocked with software.