No airbags are not mandatory on all vehicles. In the united states airbags are mandatory on vehicles under 8500 gvw(gross vehicle weight rating), but might be standard/optional equipment from the manufacturer.
Mud flaps are required on commercial vehicles in all states.
The laws about registering commercial vehicles vary from state to state. You would need to check with the Department of Motor Vehicles in your county.
Seatbelts and Airbags
1998
No, there is no such requirement for commercial vehicles in any state.
2011
On Ford vehicles the airbags typically deploy at 25 to 30 MPH, so in a head on collision, if both vehicles are traveling at a slow 15 MPH your airbags will go off
All 1998 Jeep vehicles have an airbag.
All the Buick models come with standard airbags. As a matter of fact most vehicles these days no matter what brand come standard with airbags.
It's required by law.
Airbags require replacement or service as required by the manufacturer of the car. This info is available from the manufacturer