[jpfromlondon]

In the above model prices converge on a mean, reducing the potential savings for those that price really matters (the poor are the ones most likely to check existing price discovery sites), thus it's regressive - the government are either seeing it as an opportunity to marginally increase tax rake, or more likely are oblivious to the externality of the poor bearing the burden.

[notahacker]

That's... not how markets work. The cheap petrol stations are very much aware that they're cheaper than their neighbours already. The more expensive ones may feel some downward pressure, but mostly won't.

People who are price sensitive can discover cheaper alternatives more easily; others still won't bother

[graemep]

Which model? Tested how? Are the poor the most likely to check existing sites?

This is not a new sites. Its making data more available so sites and apps will have more accurate data. This is most likely to benefit those who are willing to trade convenience for lower costs.