Driving fast and driving unsafely are not necessarily the same thing.
The violation named in the letter is "Speed Greater Than Reasonable and Prudent / Failure to Control Speed to Avoid Collision." I don't think it's a big leap from there to "driving unsafely."
What are the elements of the offense? If they only have to prove the former and not the latter, then the latter is irrelevant to the discussion. Hell, if the former is a per se rule that doesn't actually take into account what is actually reasonable and prudent (meaning, taking context into account), I'd argue the title of the statute is entirely irrelevant.