But given that I DM for different tables and different players, and only some have this issue, pretty sure it's not on the DM side.
Players are not interchangeable. Two tables with the same GM can be very different. If you want similar play patterns at both, you, as GM may need to do different things at each.
This isn't about blame. This is about how you get the group doing the thing you are complaining about them not doing.
1. It is seldom helpful when someone raises an issue, and the response is to claim that it is the pejorative "DM fault" / "Mother, may I?" scenario.
You know, I can understand you not liking the phrasing used. But... sometimes GMs aren't perfect, and things they observe may be their own fault. If you only want to engage in griping about players, that's fine, but you kind of have to let us know to restrict the discussion.
While it is possible that this is happening, it is often not the case. If it isn't the case, then the response isn't helpful, and even if it is, invoking "Mother, may I" as a first response tends to cause people to shut down. Best to inquire before labeling- especially with that label.
I have, in all my years on these boards and gaming, never seen this shutting anyone down.
And, honestly, pushing the burden of this onto the players is putting them in that dynamic, of having to ask for things when they don't really know the parameters upon which the response is based. If the GM is actively offering without being asked, it becomes much less problematic, as the players can learn the unwritten parameters.
See FATE-based games as an example. The burden of offering compels is on the GM. The players are encouraged to suggest as well, but the basic economy is placed on the GM, not players coming to ask for it.
But in the end, it comes to this: In D&D the offering of Inspiration is placed in the GM's hands What, in the rules establishes that the players should be actively seeking requesting advantage from the GM? If it isn't established in the books, it is a table rule, and the burden for establishing it is... with the GM, is it not?
2. The issue as I would see it tends to be more of the expressio unius est exclusio alterius,
I have no idea why you say that. Expression of what is excluding what?