Is "black coffee" always sweet for Thai people?

Been in Thailand a few years now, I know to order without sugar if I don't want it, but the odd time I forget and get what seems to have 5 sugars in my black coffee. For example today I went to a restaurant I rarely eat at and forgot to ask for my black coffee no sweet. I couldn't even drink it 😅.

Since my gf doesn't drink coffee she couldn't really give me a good answer about this - when Thai people think of "black coffee" is it still filled with sugar? Back in Canada black always meant nothing in the coffee. I know it's technically still black in color even with sugar. Genuinely curious if the base for ordering coffee would be similar to cha yen?