Why does a bought coffee taste so much better?
Apart from the fact I'm obviously shit at making coffee.
Because someone else has made it for you. You don't have to set up or pack up and fuck that tastes good!
Better quality, fresher coffee beans and a higher pressure machine
Lower pressure machine ... Most commercial espresso machines run around 9 bar, where as domestic espresso machines generally run around 15 bar. The commercial machine pushes like a diesel engine though.
The commercial machine allows for a finer grind and slower extraction. This gives more particle surface area contact with the water and sustained contact. By the end of a shot extraction Moe of the bean's flavour has been extracted.
If you have the chance compare the way a perfectly extracted home espresso shot looks compared to a perfectly extracted commercial shot. Generally at home you get a lot more gas in the Crema and less oil. A commercial shot will normally have more oil in the Crema. When you look at it the Crema will be denser and sit flatter on the liquid.
I use the same beans at home and work. I use the same dose and extract the same yield. The 2 taste nothing alike! I prefer the home taste with those particular beans. It is more singular on flavour and quite smooth.