I used to teach at one. Ours didn't offer GCSE & 95% of people were there for retakes or as mature students who had degrees & needed a quick A level in specific subjects to change career.
We (I believe) were good at getting people through exams. But we didn't really offer much else, the feel was very different to a school. Unsurprisingly really as we were doing something different.
However as mentioned above most of our students were 19+ it may be different in colleges with younger students but I can see why they might be described as factory like.
I loved teaching at the tutorial college, loved the people I worked with and really liked most of the students. Found it a happy place to work. But while (if I had the cash) I'd happily send my 19 year old who needed intensive retake work I'd think very carefully before sending a younger child.