This... I wonder why isn't there a market in Tijuana, Juarez and other border towns for fixing broken electronics and similar appliances.

Here in Mexico there are plenty of "unofficial" laptops/mobile (Apple, Windows, Androids) repair shops that even receive your device by DHL/UPS, fix it and return it. Because the labor costs are low enough to make it worth. The only downside is that most of the spare parts are imported from the US.