They force you to get a certain level of insurance so the logic is the same when it comes to the deductible. What’s so surprising about it? Are you sure you were allowed to have $2500 deductible on your MB?
Same reason they force you to have coverage in the first place. If you have too high of a deductible, it raises the chances you could be tempted to shirk you responsibility to have the car repaired. It’s all about risk mitigation for themselves as the captive as others have said. It’s in the contract and if you’ve signed it, you’ve agreed to it, if they didn’t ever enforce it, it would ultimately be pointless requiring it.
While $30/mo sounds a bit high to me to go from $2500-deductible to $1000-deductible… Think of it this way: if you had just one $2500+ incident in 50 months, you would be net positive financially. And that’s not even considering that the delta may reduce over time as your rates go down due to a longer incident free record.
I get wanting to save $360 a year/$1080 over the lease on car insurance, especially if you are a very safe driver, but yeah on a car that expensive it’s peanuts. Just put the insurance on autopay and enjoy the car.