This may be more of a "me problem" than a "them problem".

I often have the experience that people apologize for being slow to respond to me. Whether they're on the phone, at a counter in person, or whatever. Sometimes they say "oh dear, this computer is so slow today!" or "please bear with me while I check this..." but many times it is a very pointed and pre-emptive statement that they cannot respond or comply with my request immediately, that it may take X number of hours or days or something.

I made a special request to a vendor last year, and the CSR said "oh gosh, we need to reach out to the manufacturer, in Europe, and you know how supply chains are these days... and..." and I literally said "no problem" and eventually, they did not even charge me for the item when it came in, months later. Likewise the dry cleaner always seems to protest that they cannot finish in time and can we please push back the deadline, but I feel like they are trying to shirk my business because they're overwhelmed, too.

And I've come to believe that this is mostly the result of me approaching with impatience and anxiety. I often reach a desk while breathless and make my requests more like demands with the utmost of urgency. I am not, in fact, that impatient, but I give that impression and people believe that I would be disappointed if they take too long. But I do tend to interrupt and distract people if they are trying to collect their thoughts, or figure something out.

My last supervisor used to do this all the time. Practically every email and every voicemail was followed up with apology for being slow. And I really think that he was very gently telling me not to be so impatient and anxious.

But also, there really is a business standard for prompt replies. If someone goes out-of-office, they are usually expected to put up an "OOO autoreply" that will tell you when they're returning. Because it really is business etiquette to respond promptly, or reset expectations by explain why you'll be late.