Oh come on, this is a very extreme example. I used to work in the UK's Civil Service (which has had a decent union for many decades now) and people who called in sick too often were definitely fired, assuming this had been happening over a long period of time and all "reasonable adjustments" had been made by the employer to mitigate the issue. I saw people fired for poor performance too. Again, it had to be a pattern of poor performance over a long time with no improvement for this to happen. The union would occasionally fight these firings but their success rate was so-so. Strong union-backed employment rights don't protect people who routinely take the piss.