I’m assuming there may be a few reasons for the reduction in catering provisions on the Queen Street concourse. Namely, the large reduction in space for them in the recent refurbishment/expansion of the concourse. Whilst the station is far more pleasant, there’s nary space for any retailers!
I also assume that maximising space for customers/minimising crowds might be a part of this. If they allowed catering outlets on the station, passengers are likely to arrive significantly earlier than they may otherwise, and the new concourse can feel crowded enough at the best of times.
As for the toilets, as
@alexf380 correctly pointed out, only NR stations had their toilet charges abolished a few years ago. Unfortunately, this doesn’t apply to Glasgow Queen Street as it is owned by ScotRail.
As for other stations, I think it’s important to remember that whilst Network Rail is a public body, Scotrail is a for-profit private company. As a result, they will want to make profit from the catering offer on their trains (when they can be bothered to provide it), and putting retailers/restaurants in stations is likely to decrease the success of this (bearing in mind that the stations were designed before the catering was slashed during COVID).
Of course, this only works so far. Personally, for catering. I always use the Sainsbury’s on Buchanan St just a few minutes walk from Queen St station as they are far more affordable and reliable than the Scotrail offering. For toilets, I tend to use the free ones in Buchanan Gallery, or the one on the train.