The short answer
A windshield is more than a weather barrier. NHTSA's FMVSS 212 establishes windshield-mounting retention requirements for new vehicles to reduce the likelihood of occupant ejection in a crash. That is a new-vehicle standard, not a claim that a used vehicle is federally recertified after replacement. The Auto Glass Safety Council also explains that, depending on vehicle design, a properly installed windshield works with other occupant-protection elements.
Replacement glass must comply with FMVSS 205, but safe service also depends on the retention system, body condition, surface preparation, adhesive selection and application, glass placement, environmental conditions and adequate drive-away time. A compliant piece of glass can still be installed incorrectly. AGRSS therefore calls for vehicle assessment, compliant glass, an OEM-approved or documented equivalent retention system, current adhesive instructions, traceable materials and notification of minimum drive-away time. Cameras or other ADAS components may add manufacturer-required procedures.
