What I have found, however, with existing standardization of this kind of data (yours is not the first!), is that shopping sites (big ones) will lie, and you still need to read the HTML as ground truth.
Think of it like a cache. You use the commerce.txt for 99% of your agentic workflows because it’s 30% cheaper in tokens and 95% faster than parsing a 2MB HTML haystack.
You only 'bother' with the HTML for periodic spot-checks or when a high-value transaction requires absolute verification.
Without CommerceTXT, you are forced to pay the 'HTML tax' on every single interaction. With it, you get a high-speed fast lane for context, while keeping the HTML as a decentralized source of truth for when trust needs to be verified. It’s about moving the baseline from 'expensive and fragile' to 'efficient and auditable'.