SHOCK has turned to confusion as the details surrounding last week's bus accident come to light, with many questioning why seatbelts have not been made mandatory for all road vehicles.

Queensland Bus Industry Council executive officer David Tape explained this was "a complex issue".

"We would support any initiative that increases the safety of our passengers and drivers," he said.

"But that would be something the politicians need to move on."

Mr Tape said he felt the government decision not to require buses be fitted with seatbelts was "probably cost" as they limited passenger numbers, causing the potential for "capacity issues".

"Under current contracts, if an operator does seatbelt a bus and cause capacity issues, then the operator needs to purchase another bus to pick up the overflow," he said.

"If you seatbelt buses, then you're going to need more buses to carry existing payloads.

"So there would be an increase in the current fleet size."

Mr Tape said buses were equipped with safety measures such as padding, grip rails, ABS braking and electronic stability control.

There are also onboard CCTV cameras, but Mr Tape said there was "no such thing as a black box like you have with an aircraft".

"Those systems only record images," he said.

"You could rip those out and it wouldn't have any impact on the bus whatsoever.

"There is a safety feature that when the park brake is applied and the door is open, it has an automatic braking system there, but that engages the park brake."

Mr Tape said there was always a risk of accidents but studies done through the years showed buses still provided the safest form of passenger transport.