What the heck is up with ameteur bartenders who pour in a whole 25cl bottle?

Maybe this is just a problem where I live, but I occasionally go to parties where bartenders will pour an entire 25cl bottle of soda in a glass with 4cl.

It has gotten to the point where I ask to add the mixer myself because if I don’t, they will make the drink pointlessly weak.

And before you tell me to ask for extra liquor, I already do. For some stupid reason a standard “shot” is 2cl in my country.