What’s missing is a test that would produce evidence that would allow us to distinguish between string theory and competing theories. But that’s not nearly the same thing as saying it has “no real evidence.”
Not only do they have no proof, most of the potential experimental confirmations are at energies so high they're effectively out of reach for the foreseeable near future.
Proponents of string theory have not been able to propose an experiment that would allow them to exclude other theories, thereby demonstrating that string theory is better. But by the exact same token, critics of string theory have not been able to conduct an experiment that contradicts string theory, thereby allowing them to exclude it. And science moves forward by excluding theories with evidence (not just complaining about them).
Discussions of string theory among physicists are deeply intertwined with concerns about who gets famous, who gets grants, who gets tenure, who gets endowed chairs, who gets on TV and sells books, etc. But these types of concerns are a constant background noise to the practice of science, going back hundreds of years. Every scientist on Earth tends a private list of the wrong people who are getting too many resources to study the wrong thing.
If the critics of string theory could prove it was wrong, they would have, but they haven't yet. That makes it provisionally correct. Not correct, necessarily--it could be wrong! But it's not wrong yet, which is better than quite a lot of scientific theories proposed across the span of history (for now...).
No, absolutely not. This is the kind of argument an amateur apologist would make for the existence of God. You need to think about what "unfalsifiable" means and why it's a pejorative term in science.
I really like listening to brian greene and sean carroll but now when I listen to them, particularly in recent videos, it feels like there is much less substance to what they're actually saying string theory has done.
But who knows! Maybe I'll learn something new and completely flip my world view again, I'm not a physicist by any stretch so have to rely on listening to experts :)