I'm an old man (51) and I've had this same problem at every job I've ever had. Maybe it just comes from always being the smartest guy in the room! :-) Seriously, though, when you know how to do it right and they don't, you often think, "Hey, I'll show everybody this new and improved technique and they'll all be impressed and want to jump in to using it." But in real life, 90% of the time, you show people a better way, and they come up with a long list of excuses for why the way they've been doing it all along is better. When you demonstrate that their reasons aren't valid, they come up with new, even lamer reasons. I've had plenty of times that I've been told that an improvement that would save hundreds of thousands of dollars a year is impractical and unusable because it would require us to rename ten files and that would just take too long, or because it would require us to update the documentation, or because it would violate a company policy (that happens to be a policy under the control of someone who is in the room and who could change it on the spot if he wanted to), etc. (All real examples.) Okay, pessimistic view, but also often reality.
Even if you really are a genius, you have to accept that no one else knows you're a genius until you prove it. I'm reminded of Kris, a friend of mine who started a new job after spending 10 years with one company. Shortly after starting the new job, he was at a meeting where they were discussing some technical problem and he started to offer his suggested solution. Then someone else interrupted and said, "Yeah, thanks. Bob, what do you think?" At first he was annoyed: He knew the right answer, but no one cared! Instead they went with the opinion of someone who knew a whole lot less then he did. But then he realized, hey, at my old job, I had built up a reputation as someone who knew what he was talking about, so when I talked, people listened. Here, I don't have a reputation yet, so no one cares what I think.
I've been at my present job 2 years and it's only in the last few months that mhy opinion has started to have any real weight. You have to be patient.
On the flip side, new people often have a million suggestions for improvements that really are impractical, because they don't yet know enough about the organization and so they don't know why things are being done the way they are. Sometimes people continue to do something the same way for 20 years because that's just the way it's always been done and nobody ever thought to look for a better way; but sometimes people continue to do something the same way for 20 years because experience has shown it to be a good way to do it and every time they try something different it's a disaster. So don't be too fast to conclude all these people are idiots. Find out why they're doing it the old way before you bring out your brilliant new suggestion. I've had plenty of times in my life when I've been embarassed because I come out saying that something the company is doing is stupid and all screwed up and I have a better way, and then someone explains some aspect of the operation that I didn't know about that makes this seemingly bad method necessary, and I have to sheepishly say, "Oh, I didn't know that. Nevermind my new idea, then."