The same reason that western countries refused to buy the extremely hard to break Superfest glasses manufactured in the GDR (East Germany) during the Cold War: planned obsolescence and consumable goods mentality in the interest of profit (they got a west German salesman to take the glasses to a trade show, and nobody gave a shit, because part of the industry’s profit model at the time was the sale of new glass due to breakage.

In point of fact: better, longer lasting LED bulbs DO exist, but they’re only sold in Dubai (due to the monarchy there basically decreeing that they wanted that to happen, so Phillips made them for them, but will NOT sell them outside of the country, because it would kill their sales elsewhere).