This isn't an honesty thing. Many cultures (both in terms of social culture and work culture) have a strong aversion to saying no. Some languages barely have a word for it.
Even when those aren't issues yes/no questions rarely have the precision that you want, often you can phrase a question to seem like it only has a binary answer, but the real answer is way more complicated. Basic project management principles come into play here. As other posters have commented, asking what someone will be working on first, setting up tracking tasks etc.
I'm just a lowly eastern-European contractor banking on real estate prices in Silicon Valley remaining ridiculous on one side, and Indian contractors[0] remaining unreliable on the other.
[0] Those of them who have lower rates of course. Reliable Indian contractors have proper rates - and good for them.
That is your problem: You have not taken the time to understand other cultures.
You believe they are not being honest but they ARE!!
If they can not do the work, they tell you, but in their own language, not directly but in subtle ways.
They are expressing it, and in their mind you understand them, because they are actually saying it. It is just that you are deaf to their language, you are not looking to the nuances, and just ignore those signals they are emitting.
Even when those aren't issues yes/no questions rarely have the precision that you want, often you can phrase a question to seem like it only has a binary answer, but the real answer is way more complicated. Basic project management principles come into play here. As other posters have commented, asking what someone will be working on first, setting up tracking tasks etc.