Why do motorcycle pistons need replacement and not cars?

Motorcycles, especially dirtbikes and other types of racebikes require pistons to be replaced quite frequently, say every 30 hours of riding.

These bikes often have a rev limiter around 10,500 rpm, a little above cars like some Ferraris or the BMW e92 m3.

Why do the pistons on these bikes need replacement, while the car engines only need frequent fluid changes? If you're the owner of a car like a Porsche 911, Audi RS6 or the like, it's not rare for these cars to see high revs, especially if you live close to the german autobahn or bring your car to the track – but they still seem to have a comparable lifespan to a more modest car.

Update

Here's a screenshot of the periodic maintenance chart from the owners manual of a Kawasaki KX250F dirtbike

The 15 hours here are as many have mentioned, for racing applications and not the average sunday rider. But still, 100 hours is a huge increase from the manual and that is still quite frequent in my opinion.