system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do they make power adapters so large that it’s difficult/impossible to plug something into the adjacent plug?
gpt
Laziness and to save money. Adaptors are ubiquitous and very inexpensive and a well designed small adaptor need not cost a lot more. Most of these adaptors are sourced-in. Few companies bother to design them from the ground up. At most, they will send out an external drawing/industrial design and some reference material or finish required. 

There are good companies that spend the time to spec out adaptors that work well, fit their aesthetic and are small. They will spend a few dollars more to get it right. You have to spend more to get efficient, small form factor adaptors. 

Others just cheap out. You can get an off-the-shelf adaptor sourced with some custom labels/screen print and pay just a few dollars. (I've sourced OEM adaptors for less than 3 bucks in volume) Often times a smaller company just won't spend the resources and assign some junior buyer/sourcing person to bring in a couple of catalogs to pick from.