Some reporting is that it was one of those vehicles with a cage to protect workers from flying golf balls, like I remember seeing in Tin Cup where they were collecting range balls with a mechanism attached to the cart. Sounds like he could have been trapped where he couldn't manage to open the door.
Man dead after golf cart sinks in canal near Terra Lago in Indio - KESQ
A person was pronounced dead after a golf cart sunk into a canal near the Terra Lago golf club in Indio. According to CAL FIRE, the incident was first reported at approximately 3:02 p.m. on the 84000 block of Terra Lago Parkway. Ben Guitron of the Indio Police Department told News Channel 3 that the
kesq.com