The couple running a roadside food shop in Tak’s Mae Sot district were injured on Saturday evening when a car driven by a man from Myanmar rammed into it.
Police were seeking to determine whether Aung So, who said he’d just come from a wedding party, was intoxicated.
He claimed his brakes had malfunctioned.
Ornpreeya Rueangthip, 40, was chatting with another person when the car careened into her shop, injuring her seriously.
Her husband, Songpon Rueangtip, 42, who was cooking at the time, was injured when he leaped out of the way.