I usually buy vehicles that need the timing belt replaced. (Most people trade in or sell at that point for $ reasons). I do most of the work myself because it’s not overly complicated if you follow a manual. People at my office ask me about general car maintenance. When I ask about timing belt changes they always respond with, “Do I need to change that?” or “I have never changed that.”
At that point I ask for their mileage, it’s always way over the required service date. How many people that own vehicles experience these timing belt disasters? Most vehicles on the road are interference motors so I think the casualty rates are pretty high.
Regarding casualty rates: if this was ten years ago, I’d agree with you. But thanks to events like promoting 100,000 mile tune-up intervals in Detroit Iron during the 1990s, the majority of mainstream machines switched to the chain. This list (grain of salt: it thinks Panthers have timing belts) might help explain the time period when everyone abandoned their belts for a timing chain.
Hell, even Ferrari uses timing chains now!
To your question: we will never know how many people experience timing belt/bent valve disasters, but the numbers are likely dwindling. Impossible to prove, as car repair databases aren’t the well-organized machines seen in the healthcare insurance industry. Can you imagine a HIPAA compliant local service station?
Send your queries to firstname.lastname@example.org. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.