As a current Amazon employee I can confirm this is no longer the case or only applies to such a select few pieces of software that it doesn't actually mean what you think it does. The amount of day to day stuff that is relied upon that runs on greasemonkey scripts and web scraping is insane. API's for a ton of things don't exist or are have heavy gatekeeping. (eg. contact x to get onboarded to our API and they just g…
Sounds like they're allowing people to treat the systems as "infrastructure" and "applications" with only the infra having exposed APIs? That's super common in software of all sorts. There are a lot of people who can make good use of a decent API and appreciate it, but are not experienced (or smart, or have time, etc) enough to design a good API themselves. Most software is mortar, not bricks.
Everyone at AWS ran around with their heads cut off back when there were 6 regions because everyone was so overworked or had to drop everything they were doing for a week because a new Xen bug was published to the email list and would go out of embargo at the end of the week. I can only imagine how insane it is now with ~20 regions to support.