It's not that rare an event, and every case is entirely accidental, something anyone might do. A clever person could invent something that costs under a dollar that would prevent the internal temperature from climbing too high, maybe a shim that forces a gap in the window. Telling someone to leave the window cracked always is not effective because some people instinctively resist doing that.
We want Iran cooperation, not meddling, Gulf Arabs tell Kerry (Reuters)
from the article: Toddler dies after being forgotten in transport van in central Israel