In message , at 16:19:05 on Fri, 8 Sep 2017,
Basil Jet remarked:

Controversially, the system could be used to sell advertising, with
companies charged more to buy space on platforms where travellers spend the
longest time.

How is that controversial!

With the advertisers, who are bound to end up paying more in total.
That's the whole point!
--
Roland Perry