1. The concept of "mastery" is both relative and subjective, so if a skill is particularly common, then an aptitude which could be considered "masterful" in another field might simply be considered "experienced". In addition, for some skills there is not that much difference between competent work and masterful work; as a result, we'd be unlikely to consider someone a "master" of, say, bussing tables.
2. Most jobs are "unskilled", and those who have them are not practicing what they do with an eye toward improvement. They are completing the task to get their paycheck.
3. Jobs that do involve some skill typically also involve a fair amount of unskilled work (note that "unskilled work" in this sense can still require education and experience). They also tend to involve splitting one's time between multiple skills. Working full time as a lawyer for 5 years does not mean that you have spent 10,000 hours in a court room, much less arguing in front of a jury.
Now, with all that said, it's true that practice doesn't scale linearly such that you can simply say "you need x hours of practice". The human brain stops responding well to practice in the short-term and needs time to incubate, so practicing 40 hours a week for 5 years is probably not as effective as practicing 20 hours a week for 10 years.
Still, if you actually did practice the same small set of significantly overlapping skills full time for 5 years, you would be extremely good at those skills.
You might, if every one of those hours was spent perfecting your craft. For most of us, a lot of what we do at work is diluted by secondary tasks - meetings are the most common scapegoat.
I don't think that you'd qualify as a "true master" with 5 years of experience.