(This is mostly just a contextual fyi)
"I call the hotel and ask for accounting. I get a vm flat out telling me if I leave a message that they'll take a long time to look in to the issue. Pretty poor IMHO but I guess that's the norm. No big deal. I just hang up, call back and speak to the front desk. And that's where the circle of ridiculridiculousness begins."
If the property is corporately managed, this has been the norm for a while. Marriott farmed out a lot of their accounting functions twenty plus years ago. A full service property that in 2000 might have had four people in the accounting department, may now have one or two. Even back in the in the good ol' days, responding to outside calls/voicemails was priority eighteen on the daily top five list, I can't imagine what's it's like today.
"I aak for a supervisor. Of course, standard Marriott answer of "there's isn't one here". So I ask for the GM. He isn't there either. He even tells me he's the only one there. At 9am on a week day at a full service hotel and convention center? So should I believe him and be annoyed they're incorrectly staffed or annoyed because he's lying? I'm not really seeing other options here."
At larger properties, a desk clerk would have no clue if the GM is really there or not unless they physically saw them. As an example, at the FS property I worked at for five plus years, the GM/HR/Accounting office was in the basement, two floors below the lobby and the front desk. Best you'll get is transferred to their extension and to leave a v/m. Is it possible that there wasn't a supervisorial presence at the desk past the FDA you spoke with? It's far fetched, but in today's reduced staffing environment, it's also quite possible.
Past that, what you experienced is where the industry as a whole is going. It's why all of the parent companies push their app as hard as they do. It's 100% designed to be a job eliminator. It is an industry wide race to the bottom on FTEs both in customer facing roles and in backend support positions. Don't like it? I guess, don't leave home or don't have a problem if you do stay somewhere because resolutions that are already hard or only going to get harder as more and more things become app/AI/non-human based.