Would that many people really game the system?
I think that really depends on the work atmosphere.
Not as likely to abuse sick days:
-Workers who negotiate their salary and benefits themselves. The opposite of me whose pay is set to the same as everyone else (with the same seniority), regardless of how I perform.
-Those trying to get promotions. I have no desire to get into management.
-Those who don't have a replacement for their job (there will just be double the work for me when I get back). For my job, someone else will do my job while I'm gone and there won't be extra work to catch up on when I do get back.
-Those who can cash them out or carry them over to next year. "Use it or lose it" is motivation to use it.
-Those who are working on an important project or invention that will have their name on the work. Kind of goes along with trying to get a promotion. Doesn't apply to me.
-Those that really love their work or have alot fun at work (working is more enjoyable than staying at home). With the right kind of office co-workers I could see as being more fun to work with than doing manual labor.
But even at my job we have one guy who probably doesn't use his vacation (work there long enough you get 3 weeks, you can cash out 2 of those weeks, but everybody has 1 week that is "use it or lose it"). He's always working overtime plus he has another job, so his home life is probably non-existant.
Of course this is all generalizing, I don't want to hear from people saying "none of those describe me and I don't abuse sick days" or "all or some of those describe me and I DO abuse sick days".