HL2 NPC limited responses to the player

Is there any particular reason why NPCs, especially HL2 citizens have limited responses to the player? For example, in the HL2 trainstation maps, citizens can be interacted with by pressing the use key, however, in Gmod, they simply look at you.

I have the HL2 content, the scenes and response scripts are mounted, so I know these are not the problem.

Snooping around and debugging reveals that the responses are simply not called, and dispatching them yields no results either, except for the scenes that already play in the game, such as the citizen excusing themselves when blocking the player (TLK_PLPUSH) Worth mentioning that adding my own response scripts does nothing either.

This is a fairly obscure issue. I’ve done extensive digging in the source code to see if I am missing something, but the code suggests it should work fine in Gmod, but it doesn’t.

It seems the only way to get the NPCs to interact with the player as seen in HL2 is to reprogram a similar response system in Lua, which I have done, but it uses hacky methods since response contexts are somewhat broken as well.