And actually provide enough power.
I mean, a street lamp is usually (traditional lamp) 250 W, a modern (led) lamp 80-100 W, there is no way the existing infrastructure (cables and before them transformers) will be able to provide 10 or 15 or 20 kW (at each post).
Typically street lamps are 30 m or so apart, and in that gap at least 6 or 7 car (maybe more) park in a city.
If they become most (or prevalently) electric each post will have 6 car connected.
Even with 1/3 coincidence factor, further divided by two (assuming that people will charge their cars every two days), we are talking anyway of 6*10/6= 10 kW per post, whihc means that to power a 300 m stretch of street you need a 100 kW dedicated transformer.
And a receptacle is "lost" for the whole night (or day).
I mean, you come back home around 19:30 and plug your car in a lamp post power receptacle, even if your car is fully charged after - say - 4 hours, are you really going to go out at 11:30, unplug your car and move it to another spot (IF there is a free one) in order to allow another person to charge his/her car?
And how long will be the charging cable (the one you have on board)?
It must be at least 20 m long to reach the lamp post if the parking spot you find is in the middle of two lamp posts.