First, throw money at it by forcing us to buy them, then see what happens. When people start getting injured or killed by them, add warnings and regulations. Government passes mandatory seat belt law. People still don't wear seat belts. Government requires passive restraint system on cars.
Some car manufacturer go for air bags, some for automatic seat belts.
People hate automatic seat belt more than the manual ones. Car makers go with the air bags. People still don't wear seat belts. Air bags start killing people. Government adds rules, regulations, and punishments for air bag use.