system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are there so many different bolt and screw designs (Hex wrenches, flathead, etc.) ? Wouldn't it be easier to have one universal tool?
gpt
No, All have different uses, and in turn are optimum for different types of jobs. Moreover cost can also be a driving factor for what to use. And lastly whether your screw driver, impact driver, hammer drive, etc... will slip should also be considered. 

For instance Lag Bolts (Giant screws with hexagonal 'nut' ends) are great for anchoring 2x4 shelfs that will support ALOT of weight. Since they can be 3", 4" or 6" and beyond - you need to use a socket set with an impact driver to really make sure that bolt will not slip. 

Alternatively, if you were framing a deck, and needed 2.5" screws Philips will work just fine - but green deck screws should be considered (costly) and the t-25 bit "star shapped" will not strip easy (and again will cost more). 

Right tool for the right job, bro.