In Spain most city roads with 2+ lanes per direction have a dedicated bus lane, yet you still get bus bunching and spacing adjustments anyways.

- Imagine bus A is followed by bus B, it's 5PM and people are leaving work simultaneously

- Bus A spends a lot of time on each stop picking passengers up

- When bus B arrives, fewer people are waiting and it tends to take less time

- Eventually, bus B catches up to bus A so A must skip stops to maintain proper spacing

As for why this doesn't annoy people: if both buses are already close together, any ETA changes from spacing adjustments are minimal, and bus A will show no destination on the front display, so no false expectations are created.