It needs to be a fairly wide section of pavement to install these types of planters without causing an obstruction and without a risk of them getting knocked over by passing cars. On the other side of the road bus stops take a bit of a battering from passing cars.
But these tyre towers are an interesting test to see how they are received and how well they survive. Plants have been deliberately chosen that do not require lots of water or maintenance. So if these work well then perhaps local people would like to suggest other locations and even assist with the maintenance.