Why doesn't the LM7805 circuit short circuit?
Capacitors do not present a short circuit path. The Capacitor will charge then stop when full, acting as a parallel voltage source when the Input voltage source drops for whatever reason.

And electricity does not just take the easiest path, or path of least resistance. Electricity will flow through all parallel paths. You may see a greater current through one path due to its lower resistance, but it will go through other paths too.