Hot car accidents -why has tech not come to the rescue yet?

The 1 year old twins who died in their dad's hot car in Bronx after being forgotten by him are the 24th case of infant deaths in hot cars just this year. The average is 38 cases a year. It's understandably a really rare occurrence to forget your child in your car, but a horrifically tragic one if it does happen. This is easily preventable by simple tech like motion sensors or alarm systems to tell the parents/ care givers that hey, you can't lock your car, you're kid's still in their car seat. Or an alert if any motion is detected in the car once you've left it, there are so many simple possibilities. Why is this not a law enforced mandatory safety feature of all car seats yet? Why are we still having such tragic, easily-preventable deaths in 2019? Would love to know if there are any companies working on this. As a mom of a toddler, out actually as just a human being, it's disturbing to see babies dying when we have the technology to prevent such accidents.