Waymo doing select trial, or perhaps even limited runs above 25mph does not prove they can operate safely at such speeds. My math might be off since I don't use the imperial system, but LIDAR is only good up to 50-100m (closer to 50 than 100).

Slamming the brakes on your vehicle to stop within the sensor distance is more dangerous (to the occupants and cars behidn you) and less effective (less likely to stop in time) the faster you're going.

Can you go significantly faster than you can safely see and stop in time? Sure. Would it still be considered safe when doing so? Hell no.