In the concentrated area of London we now have hordes of cycle commuters seen at times SRS, but they are still a very small proportion of the population, I don't see propaganda changing that in our culture, the great majority simply don't see bicycles as utility transport.
The general view is that bicycles are for leisure sport, such as lycra clad for club road riding, as off-road mountain bikes to play around on or BMX for stunting,
Cycling for transport is seen by most as dangerous in today's traffic, as impractical in our climate, as tiring and uncomfortable. One can't use a bike to run the kids to school or take them to their activity centres, and many, often most, won't allow their kids to have their own bikes in view of the traffic dangers. Bicycles won't carry husbands, grandparents etc for various purposes such as taking them for a hospital appointment, nor are they practical for longer journeys. A car is ideal for the large weekly shop, especially when the weather is bad, and a cycle trailer will be a step too far for a non-cyclist.
Since most feel they have to have a car to carry out the things mentioned above, understandably they see no reason not to continue using it and not complicate matters with a bike as well. Almost always when I've suggested a bike or e-bike to one of the motorists in my area, the idea is just treated with polite amusement. That's our UK culture.