The reality is that the ratio of "total websites" to "websites with an API" is likely on the order of 1M:1 (a guess). From the scraper's perspective, the chances of even finding a website with an API is so low that they don't bother. Retrieving the HTML gets them 99% of what they want, and works with 100% of the websites they scrape.
Investing the effort to 1) recognize, without programmer intervention, that some random website has an API and then 2) automatically, without further programmer intervention, retrieve the website data from that API and make intelligent use of it, is just not worth it to them when retrieving the HTML just works every time.
edit: corrected inverted ratio
Right - the scraper operators already have an implementation which can use the HTML; why would they waste programmers time writing an API client when the existing system already does what they need?
Also I wonder if the ToS covers "queries & interaction" vs "uploaded data" - I could imagine some tricky language in there that says we wont use your word document, but we may at some time use the queries you put against it, not as raw corpus but as a second layer examining what tools/workflows to expand/exploit.
There’s a range of ways to lie by omission, here, and the major players have established a reputation for being willing to take an expansive view of their legal rights.