I think a good way to think about this is to turn it around. Whatever your job is - operating a machine, handling a certain kind of documents, etc. - do you think it could be done better through democracy within the company than by yourself? You who obviously have the education and/or talent for it, since you were hired, and the first-hand experience of doing it for however long you've been doing it.

Probably not. And just the time it would take to vote on every button to push, every word to write, etc. would slow things down considerably.

The same goes for the people deciding. That's their job, and if they don't do it properly, they, just like you, risk not getting a raise, getting a pay cut, or being fired. Only not by a superior in the company, but by the market.

@TheGuySwann This reply might interest you too, tagged you in case you don't get notified otherwise. 

 I never said democracy was a good idea. I just pointed out that without it you have usually get tyranny.  And that (from a societal point of view) is worse.  But throw in Capitalism and that ususally becomes guaranteed.  Name a large high value corporation that isn't tyrannical. 

 True, there probably are few to none. However the tried alternatives have been worse (see the Soviet union or East Germany). I don't know if there is a solution that's actually good. Some think that in a perfectly free market, corporations wouldn't grow to such sizes, but I doubt that's correct.