10-15 years ago, advanced safety features didn’t exist

5-10 years ago they existed, but only at the higher trims, or with an add-on ($$$) package

Most safety features are now standard.  Even the lowest Prius trims come with:

• Backup camera
• Rear cross-traffic alert
• Blind spot monitor
• Safe Exit Assist
• Pre-Collision System w/Pedestrian Detection
• Lane Departure Alert w/Steering Assist
• Lane Tracing Assist
• Dynamic Radar Cruise Control
• Road sign assist
• Automatic High Beams
• Proactive Driving Assist

The only safety feature that's standard on the highest Prius trim (Limited) that’s not on the LE is parking assist, which is arguably not really a safety feature anyway.

Most of these features aren't mandated.  Here are the mandates and when they took effect:

• 2018: backup camera
• 2009-11:  Electronic Stability Control (ESC)
• 2005-07:  Tire Pressure Monitoring System (TPMS)
• 1998: Airbags
• 1990s-2000s:  Anti-lock brakes (ABS)
• 1960s: seat belts (thank u Ralph Nader)