Can my dog drown in a kiddy pool?

I have a 6 year old grown male golden retriever who loves water. He’s had kiddy pools all his life and never drowned (he’s obviously always been watched when in the kiddy pool) but in summer he likes to lay down in the shallow water and play in it. But this year, my mom decided that he’s not getting a pool this year because “there’s a huge risk of him drowning”. Any truth to this?