Unfortunately due to HR laws and silly modern bureaucracy, it is very difficult to fire someone if they are incompetent. It is easier to do so if they did something really bad like harassment or fraud but incompetence is not really something you can get them on. It is too much of a massive bureaucratic hassle that may proof more of a burden and risk to the manager than the 'unreliable' employee. As a result, many managers would rather suffer an incompetent or lazy employee than do something about it. My previous company was notorious for that.
I say you are lucky it's being done at all. I know of 'lifers' who have been doing a half assed job for maybe 10 years and still there.