IDF and border walls block it and essentially apply an embargo on outside trade. Imagine living where imports and exports are blocked and you need an exit passport to leave. https://en.wikipedia.org/wiki/Blockade_of_the_Gaza_Strip
That was mostly about the Gaza strip not the West Bank. In either case both have borders with other countries. Gaza has a border with Egypt and the West Bank has a border with Jordan.
You're right; my post was incorrectly about Gaza and not the West Bank. Gaza definitely is a more perilous situation given it is so small and cutoff from the outside world. That is not to say the West Bank is markedly different, but merely that there are at least many cities and a larger territory, so there can be at least some commerce and opportunities.
In both cases all borders--whether with Israel or neighboring countries--are controlled. Shortages of fuel and medical supplies occur. Roadblock checkpoints exist between cities to slow travel and limit freedom of movement. A significant portion of the population are refugees whose homes have been destroyed or who have been forced out of their homeland. The correct and neutral word to describe the situation in the West Bank truly is military occupation.
Why isn't the mail coming thru Jordan (adjacent to the east) instead of Israel?