Zero Price. One argument for zero price is that there are positive externalities and network effects for bringing everybody to the same high level service. A second is And that leaving poorer citizens and lower margin business behind is less inclusive.
Clearly charging those who can afford would make it less costly to the taxpayer, and be less regressive, but it is messy. But surely over time that would emerge? And behavioural insights might help design 100% take up with mostly positive pricing.