This is like complaining that your screwdriver is bad at measuring weight.
If you really need an answer and you really need the LLM to give it to you, then ask it to write a (Python?) script to do the calculation you need, execute it, and give you the answer.
⌴⌴⌴
That's a problem that is at least possible for the LLM to perceive and learn through training, while counting letters is much more like asking a colour blind person to count flowers by colour.
Why is it not possible? Do you think it's impossible to count? Do you think it's imposing to learn the letters in each token? Do you think combining the two is not possible.