Behavior change is how UX makes its impact. Have a sense of what people will do differently due to the changes you make. The bike thing is an illustrative example - even though it makes the road narrower *it also gets cars off the road* because it changes behavior. Otherwise it would be useless.
Those who claim bike lanes slow traffic either don't understand the facts or don't care about them b/c they simply dislike cyclists.
Either way, they're wrong.
www.cbc.ca/amp/1.7358319