I too have never come across a driver who couldn't be bothered to enter a PIS code into the system. They aren't the most reliable of systems though and there are therefore frequent occasions when it is necessary for the driver to take over announcing. I personally have no issue with this, in fact I quite like doing the announcements, but in terms of what you might term "cab workload", announcing is the lowest priority. In other words a driver must not let announcing distract them in any way from the driving task. Where I am, this is understood and encouraged by management. 95% of the time it is perfectly possible to announce station stops but if I'm experiencing low adhesion, dealing with a GSMR message, blowing up for track workers etc then an announcement will be missed.
As a slight aside, I often see moans on Twitter about explanation/apology announcements not being made on slow moving trains (DOO). The fact is that I and many other drivers will not make PA announcements when running under cautionary signals. It is too much of a SPAD risk. I will happily let the pax know what is going on if I have actually come to stand at a red, but otherwise when running on yellows and double yellows the announcement has to wait until I am once again running on clear signals.