it's different because you'll never get EVERYONE to agree on one set of standards. if you don't like what you have, replace your fasteners. If you can't find a matching size, redrill and tap your holes, then replace them. OR, you can deal with it, accept the fact that it's never going to standardize, and move on. I can adjust every fastener on my bike with 4 tools: that's crazy. I'm a locksmith by trade, and I can't think of many pieces of hardware that adjust with only 4 tools... different types of screws/bolts/whatever need different types of drives. manfuacturer's go with the cheapest they can, and since your bike probably wasn't built stem-to-stern by the same company, they'll all have different suppliers of their 'cheapest' fasteners.