The problem with these examples is that you haven't provided a context, so it's difficult to evaluate them. But I'd suggest that all contextualised examples can be explained by the distinction between continuous (or repeated) events vs single occurrence/permanent events
1a. She's turned vegan. She hasn't been eating plant based foods since July or She hasn't eaten plant based foods since July.
(both continuous and
expected to be permanent, so depends on speaker perception)
1b. Let's go to the Chinese restaurant. We haven't eaten there since July.
(No single occurrence/ permanent during the stated period)
2b: She was very nervous before her presentation. She hasn't been speaking in public for very long.
2b: I think I must have offended him. He hasn't spoken to me since July.
(No single occurrence/permanent)
So both 1a and 2a can be considered "intentional" and either form can be used, while 1b and 2b are "co-incidental" and only the simple form is possible. But I don't think this is the most important distinction.
Have a look at this presentation on aspect
. It may clarify things a little.