You might be very interested in the following talk, where a Marriott tech lead describes how as recently as 2013 (and it's ambiguous, but it's likely still the

You might be very interested in the following talk, where a Marriott tech lead describes how as recently as 2013 (and it's ambiguous, but it's likely still the case), much of the Marriott pricing engine was running on a single "green screen" (his words) IBM mainframe. He speaks about how only in ~2014 with a management shakeup did culture begin to shift towards acceptance of open source components. But, as we all know, these types of organizations don't turn on a dime, and sadly this breach is likely to make them more conservative (and increase reliance on those old-school systems) rather than less. I'm not surprised at all about your experience. https://www.youtube.com/watch?v=wdFYEuWWpzo&t=5m30s https://www.youtube.com/watch?v=wdFYEuWWpzo&t=5m30s Disclosure: I'm working on a project (currently stealth) in the alternative accommodations (vacation rentals) space. Lots of people all over trying to reinvent these types of booking engines, and it's a tough challenge to get right. I don't blame them for not wanting to deal with distributed systems on top of those challenges. But IMO that's part and parcel of a modern approach to the problem.