Comparing passport power by total number of countries you can enter is a bad metric.
The UK has a much higher rating than Chile because Britons can enter countries like Lesotho or Namibia visa-free. On the other hand, Chilean citizens can enter both Russia and Iran without a visa, which I think makes it more powerful.
IMO, the countries passport holders can travel should be weighted by: 1) their size and economic strength 2) attractiveness as a tourist destination.
For example, right now, Estonian and Polish passports have the same score. However, Estonians do not need visa to travel to the USA, while the Polish need it. This is arguably a significant difference.
How exactly countries should be weighted is a separate debate.
The UK has a much higher rating than Chile because Britons can enter countries like Lesotho or Namibia visa-free. On the other hand, Chilean citizens can enter both Russia and Iran without a visa, which I think makes it more powerful.