Years ago when I started, 1968 at least two things were different than now. First there were more flight schools, most every big airport had one in the days before the TCA chased them away from major airports within cities.
So there was competition, if a CFI at one school did not value a student,that student could go to another school.
And I think there were more students, maybe just more people interested, or it was cheaper, or maybe the GI Bill helped.
But, in any event CFI seemed to have a different attitude toward a student solo. The solo was seen as a step when the student had basic knowledge and control of the plane, enough to fly around the local pattern and make 3 landings. It didn't mean the student knew everything or that more learning was not on tap.
I don't think all CFI s are like that now.