donquijote1954 wrote:

Why do you think that bike lanes are safer than the carriageway? And why
do you think the carriageway isn't safe?

Because the SPEED DIFFERENTIAL is too great...

Why is speed differential important?
A speed differential above 20 miles per hour begins to present safety
concerns. When the speed differential approaches 30 to 35 miles per
hour, the likelihood of a collision between fast-moving through
vehicles and turning vehicles increases very quickly.

At that speed, you don't have turning vehicles, only vehicles changing
lanes.

Rear-end
collisions are very common on roads

In the US? Don't know about that. Here in Germany they occur mostly at
the end of traffic jams.