Both drivers admitted their wrongdoings in fixing temporary door latches to the vans’ backdoors and replacing car seats with plastic chairs to cram more children.
Tran Thuc Dinh was fined VND2.75 million ($119) after three first graders fell off his van in the southern province's capital Bien Hoa on November 26.
Thinh had removed seats from the vehicle, driven it without a fire extinguisher, and carried passengers without commercial contracts, police said.
His managing company was fined VND17 million ($737) and suspended for two months.
The other driver, Cao Tuan Viet, received a heavier fine of VND13.9 million ($602), after two fourth-graders fell off his van on Highway 1A on November 29.
Viet's violations included driving without a license, driving uninspected vehicles, carrying passengers without commercial contracts and removing seats. He was not affiliated to any firm and was acting on his own.
In the most tragic instance of unsafe school bus practices to date, a first-grade boy in Hanoi was found dead in August this year after being abandoned inside a school bus for nine hours.
In September, a three-year-old boy in Bac Ninh Province in northern Vietnam luckily survived after being left inside the bus with a window open 10 cm wide for eight hours.
Both the bus driver and the bus monitor in the Hanoi incident have been arrested and are facing charges of involuntary manslaughter. In Bac Ninh Province, the kindergarten was suspended.