Why no article with "service" and "access"

Simple question, which I'd like a simple (simple enough to explain to an ESL student) answer to.*

Is there a conference room?

Is there a non-smoking room?

Okay, so I have no problems with these. But then:

Is there Internet access?

Is there room service?

Why don't we use the indefinite article with these words (access and service)?

I've boiled it down to "they're both kinda nebulous things you can't count", but that doesn't help me much. Is it just that they are uncountable? Because I have a feeling I'm going to have a conversation like this:

Student: Why is "room service" not countable?

Teacher: Well, there are many services offered - food, laundry, cleaning. The word "service" covers many individual services.

Student: So why not call it "room services"?

Teacher: Ah, well, you see, that's because of - Goodness me, look out the window! Is that a tree?!

Similarly, why do we say:

Is there air conditioning?

I understand that some things are countable and some aren't, but in this case I'm having a hard time figuring out how to explain it to the student in a way that's vaguely logical. I don't want to have to say that it's just the way it is (like spellings and irregular verbs) unless I absolutely have to.

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*I'm aware it almost never works this way, but I have my fingers crossed, so you never know.