Location, Location, Location

From The Evening Standard:
One of the world’s most famous advertising hoardings is up for sale for the first time in 24 years.
The prime slot on the Piccadilly Lights, the electronic display at Piccadilly Circus, is on the market after Japanese firm TDK’s contract ended.
Insiders suggested Land Securities, the owner of the celebrated London landmark opposite the Eros statue, could get in the region of £4 million a year for the spot, which measures 21.1 metres by 4.8 metres.
That's a lot of money - and that's only one out of six spaces. And why is the site so valuable..?
Outdoor advertising consultancy Wildstone is advising Land Securities. An estimated 2 million people a week pass the site.
And how do 99% of those people get to Piccadilly Circus? Using public transport is how.
So why shouldn't Transport for London send Land Securities an invoice every year, and charge them (say) 10p for every person passing the six spaces each year, £10 million all in?