If your roadway is designed so that the average driver only feels comfortable going about 30 km/h / 20 mph, you don't really need to have separate cycle lanes because bikes can match car speed.
Correct, and same with e-scooters over where I live, which is how I know that most cyclists ride at about 20 km/h or less - by reading the speedometer while matching speed with a cyclist in front of me.
