The problem is not the cable and conduit which is relatively inexpensive. Unless you're going to install just normal 3 pin outlets (assuming everybody drives around with a level 1 charger in the boot) you'll need level 2 EVSE - most can supply two vehicles - so that would add the cost of 25 devices. Most of this equipment for most of the time is going to sit there completely unused which has a large opportunity cost. 

I think the root problem you identify  is providing "enough" car parks for every car on the road. IIRC that number is about 7 per car, which goes to show that by itself electrification of the vehicle fleet only solves a very small  part of the numerous issues that car dependency imposes on society.

Much better in my view to use that vast expenditure to provide transport alternatives alongside dedicated EV charging bays.