It's a bit difficult to create a healthy and well-developed society when it gets periodically bombed and access to even basic supplies is restricted by an occupying force.
Do you want to catch fish off the coast of your own land, in waters that are meant to belong to your country? Too bad. If you go too far your boat gets blown up or you get shot. (And the definition of 'too far' is really determined by the person firing the weapon).
Do you want to walk on your own land, but happen to live within sight of the border? Better be careful - if you get too close for the liking of whoever's monitoring that bit of land, you'll get a bullet in a knee or in your head. Oh, and if your small child happens to stray into that space, their age is no protection from a sniper's bullet.
When you're pregnant, would you like your doctor to have access to the necessary medical and surgical supplies to ensure your baby can be delivered safely and receive any necessary medical care? Well, that could be tricky - a lot of those supplies are classed as 'potential dual use' and get turned away at crossing points.
Would you like a sleeping bag? Well, you can't have a green one because green is a military colour so gets rejected at the crossing points. (Seriously, lists of banned items have included green sleeping bags, children's crayons, and similar items)
Would you like to leave the area yourself, maybe to visit loved ones elsewhere? Well, that's going to be tricky in terms of organising approvals, unpleasant in terms of the sexual harassment most women experienced at crossing points, and risky because there's no way to ensure you won't be abducted, arrested or denied re-entry.
Etc.
But clearly people just haven't been trying hard enough.