How do you get a dog to not be "bothered" or interested in other dogs?

When I go out walking I see people playing fetch with their dog and no matter what dogs are around their dog does not take a bit of notice.I have met people that have gone to socialisation classes and it makes their dog friendly, they still like to go and meet other dogs. How do I get mine like the others and not care instead of curious?If the answer is training, then what type of training?

I think it has something to do with bringing other dogs around them at a young age

Certain commands such as "ignore it"/"leave it" or "watch me" are useful in situations such as this.

Simple... socialization is mistakenly thought to mean play time. That's not necessarily what it is. If you make it play time every time your dog comes in close proximity to other dogs, then other dogs are automatically associated with play and crazy time. If a dog is to continue focusing on accomplishing a task in the presence of other dogs, then allowed to meet on your terms and play only when you allow, they learn that other dogs are meaningless background chatter until you say differently. In my opinion it's not a bad thing to allow dogs to meet but they shouldn't be allowed to jump all over eachother and play in every instance. They should only be allowed to get close and sniff when they are calm. Sometimes it can end there and you walk away, and sometimes you can allow them to play a bit. The dog should learn, pleasing you is a priority and not meetin other dogs. If they are allowed to meet and greet, you will allow it. If they are allowed to play, you'll give permission. If it's not allowed today, no crazy or wild behavior will change your mind.

Part of your answer is in your first "observation" above: "people playing fetch with their dog". The people have established that they, themselves, are much more fun and interesting than other dogs. They have developed a game whereas the dog is playing/working with them. Dogs react off of action; something moves, they chase. And running can be great fun! So, why utilize it? Run tourself with your dog, use a toy....be interesting and fun!Your second observation: right. "Socialization" should not be training your dog that everytime he sees another dog he is allowed to, or can run away to play with it.Obedience classes. "Heel""come"" stay""leave it"