Travelled, did you actually see any halls in Liverpool?
My DS has just finished his first year (and had an absolute ball!!) - at his offer day we went to visit the off campus catered halls, as well as on campus SC, even though he had no intention of going catered (but just in case!).
The difference is stark - the catered we saw are very old fashioned, reminiscent of my halls in 1981. I think they are being updated/replaced, but probably not for this years intake. They are also a good couple of miles off campus, and the city.
The SC by contrast, modern, warm, great facilities, not to mention close to lecture theatres, the city and Lime street. The latter 2 were important - lots of times we messaged DS and he replied "just wandering into city with x,y,z to do/see a,b,c" (not just the clubbing and nights out, though he had plenty of those). All part of socialising and firming up the friendship group in year 1.
As for the station, we are close enough for him to come home overnight midweek when more convenient than weekend. Given that his room was 10mins from the station, then another 5 to lectures, he could easily arrive at Lime St at 9.30 for a 10am lecture, dropping his bag in his room on the way! Obvs only relevant if you are reasonably close to Lpool, but something that didn't enter our heads when looking at accommodation.
I have often read on MN that they make friends more easily in catered. Well all I can say is that it took me almost a term in catered to make friends, compared to DS who met his quite large friendship group at welcome drinks on first night. None in his flat, all in flats above, below, but he is moving out with some of them and all still good friends.
I realise there are lots of things to consider when choosing halls, not least cost, but if SC are within her grasp, then I would say go for them.
One thing we have noticed, is that DS has generally eaten later at uni, 9ish, compared to 6-7 at home. I think he liked to get work done then cook, but maybe something to consider if catered have rigid meal times. I am sure that nights out and later breakfast/lunch also had a bearing on the late meals too.
Feel free to PM me if you need any more info on Lpool, or your DD wants any info off my DS.
I am sure she (& you!) will love Liverpool, DS has and we have certainly loved visiting him.