Speed bumps are much rougher in my idiot monster truck than they are on my Mercedes station wagon, idiot monster truck spring rates and damping are engineered to tow heavy loads/carry heavy payloads so especially when unloaded speed bumps are quite jarring compared to a passenger car.
Just hit them significantly faster, it'll do the same thing as going slow with a heavy load. There's a reason the faster you ride motocross the harsher you tune your spring and damping rates.
Off-road trucks have better bump handling ability as their suspensions aren't configured like load handling trucks.
Except for the fact that the in the average case the monster truck is probably being driven by someone who'll full send it (which minimizes the bump) and the Mercedes is being driven by someone who'll inevitably crawl over it at 2mph.
But yeah, swap the average drivers and the Mercedes is gonna do way better.