"Underutilized" is a pretty iffy measure when comparing parking to bike lanes. Let's say 10 drivers can park on one side of a city block. Their cars will be parked for an average of 2 hours, and will carry 1.5 passengers. The parking is heavily contended for 14 hours. Given these rough estimates, 105 people will benefit from the parking each day. How many cyclists need to use that same land per day to be considered properly utilized? 200? 500? The fact that a bike lane isn't congested doesn't mean it's underutilized relative to parking.

And let's not forget that bike lanes are a public good, while parking spaces can be (and are) provided by private businesses. For that matter, the city could provide public lots or garages that are off the road. Parking does not need to be curbside.