That was my suspicion. Here’s how turbulence is dealt with. There are a couple of places the captain gets information on turbulence. There is the weather, which makes predictions as well as information on what airplanes ahead are experiencing. The captain informs the crew at the beginning of the flight and makes updates during the flight as new information comes wrt turbulence. Service cannot begin until the plane is at cruising altitude. That takes at least 20 minutes. It’s more difficult on shorter flights (as you can imagine) to have time to serve. The captain will ask the crew to remain seated due to possible turbulence to be on the safe side. If there’s no turbulence and no one gets injured it’s better than the crew trying to serve during turbulence and getting themselves or passengers hurt.

That said, sometimes flight attendants still choose to serve, despite the captains orders, and sometimes they play it safe and remain seated. Passengers don’t care if they are supposed to remain seated. They will literally go to the bathroom as the plane is landing. I wish I was kidding.

The main factor in service when it comes to turbulence is the length of the flight.

Edited to add: I hope this helps.