Rather then the NEM pocket . I presume you are referring to tension lock couplings. These are a legacy of train sets and table top radius curves. Also in our stock, unlike the US, the buffers play an important role in real life and hence you have a conflict between a buffer- less system like buckeye and our buffer and link approach. In models historically buffers played no role , and one of the main issues was to prevent them locking under tight curves , this was one of the main features of TL couplings, and has also dictated the approach of other couplings .its also the reason they are fitted to the bogie rather then the buffer beam
The problem has been what to substitute them with. Buckeye is , until recently , completely unprotptypical , but at least the kadee is small. Also it's also unsuitable to certain rolling stock when run on tighter curves ( or operated over tight reverse curves like crossovers ). US rolling stock , due to poor track , went predominantly to bogie based stock , whereas we can have long( ish ) fixed wheelbase stock. This further complicates things.
There are a number of other more scale orientated couplings , particular Spratt& Winkle , Alex Jackson and Dinghams , all of which are not compatible with the NEM pocket and require careful fitting. All , as well, limit the radius over which they operate, especially for coupling /uncoupling actions
There's no easy answer
Dave