https://sprintervanusa.com/2016/08/25/four-wheel-drive-in-a-sprinter/
"The U.S. system also does not have differential locks. Instead it uses sensors that apply the brakes on wheels that are spinning. This has a similar effect to a diff lock without causing issues when you want to turn a corner. Traditionalists seem to be really upset about this, but for most places you’ll take a Sprinter, it’s unlikely to make much difference. As John Shmit on the Sprinter forum says, “Old Russian saying : The better 4×4 will make you walk longer to find the tractor.”