Why does my bike constantly break/need servicing?
The bike you have is a decent low/mid-range hybrid bike with entry-level name-brand components. It should absolutely be mostly trouble-free with basic maintenance for a daily 4 mile commute. While replacing the cheap plastic pedals with a decent set of metal or high-quality poly pedals is standard business for any new bike, the other problems are worrying. 

To be honest I don't think it was assembled correctly at the shop, and the mistakes in assembly - mis-alignment of the derailers, improper torquing of components (too loose for the bottom bracket and crank, too tight for the chaincase), etc. - are causing new issues to pop up on the regular. If you bought the bike from the shop who's been fixing it, find another shop. Heck, find another shop, period - any pro bike mechanic worth their salt should be finding and fixing these issues on their work-stand before you find them on the road. 

It may be that there are so many problems on the bicycle that need remediation, a new or gently used bike might be a more economical solution than trying to bring this one into some semblance of repair. Find a different shop to buy it at and to maintain it.