You're right, but the parent comment was asking about the exception to that majority.

There’s a million reasons besides tariffs a cost may increase. Sellers with no tariffs will just increase prices to pad profits if they’re given an opportunity to let Amazon pin it on tariffs. There is a lot of evidence supporting the theory that this type of manufactured inflation is what drove the recent pandemic era inflation. Corporate profits alone are the best indicator of this occurring. They raised prices by a lot more than their cost increased because they could hand wave broadly at inflation.

It is complicated because tariffs are not just "passed off". In the real world, tariffs are almost always marginal, meaning each company is willing to absorb some of the cost, ie lower profits. In parent's example, the US has a large steel industry and rail companies relying on imports cannot arbitrarily raise prices because they need to stay competitive with companies using domestic. Markets are also dynamic and simply comparing pre/post price may work temporarily, but for a persistent tariff that metric will become increasingly meaningless as price inevitably fluctuates due to other factors.

Prices fluctuate all the time especially on Amazon items. Inflation is also a factor. Just taking prices from Jan 19, 2025 as a baseline and attributing all other changes to tariffs isn't going to be accurate.