I'd like to take this moment to point out that "I.T. workers" is a bullshit category. It makes as much sense as putting theoretical mathematicians, rocket scientists, and accountants all in a category because they all "do math", or (house) architects, construction workers, plumbers, electricians, and landscapers all in one category because they "make houses".
Here's a partial list of things I've done for work as part of an "I.T." job:
* Website design
* Malware removal
* User account management on a Windows domain
* Physically cannibalizing one rack-mount server for parts to put in two others
* Writing code in a programming language (not to be confused with writing HTML/CSS)
* Go through crash dumps in a debugger to figure our what happened
* Black-box test web applications for security vulnerabilities
* Review design documents for security risks in the designed software
* Research new test tools and make recommendations
* Write reports (on a computer!) related to the above
No two of those things are the same skill set. I'm not including things that bridge some of the gaps, like writing scripts (coding!) for automating some test tools (black-box testing!); those things may require skill in two different tasks, but the tasks themselves are mutually independent. I'm not even including things that every field has to deal with that aren't really the core skill, like interviewing people, managing project schedules, interpersonal communication, etc. I'm also leaving out a lot of fine-grained differences in things, like the difference between worrying about performance in a driver (where you want memory and CPU efficiency, avoiding long blocking operations, etc.) and performance in a web app (where you want scalability through parallelism, caching, offloading work to the client where possible, etc.). Some of these items might be broadly categorized as being in the same kind of field ("Tech Support" or "Software Security" or "Development") but even there the skills needed, aptitudes an individual will have, and interest levels vary wildly between tasks.
I love my current (sixth, counting college internships) job overall, but that doesn't mean I enjoy the report writing or am good at network pen-test just because I can find XSS in damn near any web app and can reverse engineer phone apps. My second and fifth jobs were disasters for very different reasons, but both boil down to "I wasn't doing what I was hired to do, and was being told to do things that I had no knowledge of and/or interest in" and poor management (one wouldn't define objectives, the other didn't understand that you can't just have two people do the work of five, without the deadlines changing, simply because the other three quit). So yeah, sometimes you can group the jobs meaningfully and compare the specific instances (jobs five and six are similar, though there are a lot of differences even so). But it doesn't even make sense to group jobs two and five (beyond "was working on software-related stuff") any more than it makes sense to group a theatrical stage lighting director with an electrician (even though they both work with light bulbs).