Without denigrating the need for bike safety and separated lanes, I really wonder about the numbers on the carbon trade-off there!
One problem with just going by your impressions is that cars take up an awful lot of space and a road can look full of cars, even if they don't represent a majority of people. On the typical NYC (or Boston) street, pedestrians outnumber cars 10:1, but get much less than half the space. For another example, the Dan Ryan Expressway in Chicago has 7 lanes in each direction, and two subway tracks in the middle. The subway can (and likely does) carry more people than all the expressway lanes.
Another problem is that in urban settings specifically, the capacity of a road is pretty much always limited by conflicting traffic at intersections, and so the exact number of lanes doesn't actually make a difference as long as it's enough to feed cars through the green lights at an optimal rate.
It actually kind of reminds me of the old "nuclear deterent" theory. The idea that if you attack me, I'll create nuclear armagedon. If there was a way for Germany to produce so much CO2 that everyone would die, then maybe Germany could tell the US, "if you don't stop producing CO2, we'll produce a lot of it ourselves". Really, I don't know though. So far, I'm not optimistic.
[1] https://en.wikipedia.org/wiki/List_of_countries_by_carbon_di...
So why did they take away the car lane, if not to make bike lanes? From what I've read, and observed here in Redmond, WA, is that the current fashion is to reduce four lane streets to three lanes (two directional, one center turn lane). The goal is to slow traffic in residential areas and...I forget what the other goals are. Anyway, it's a thing now. In your situation, perhaps they took away lanes to meet the current fashion, bike lanes just being the icing on that cake, or maybe they really did do it put bike lanes in.
Not all countries and people are the same, so what maybe be enough incentive for 1 person or culture (oh, they made bike lanes? I'm going to bike to work now! versus oh, the road still has cars on it? I'm not biking, because it's not safe!) is not enough for another.
Either way, the only one to blame here is the local government for either not doing enough research initially or not incentivizing people to use bikes over cars enough (e.g. we'll pay 50% of your new bike price up to $X )