Re: “frivolous applications”
It would, however, help if public universities would be more transparent about admissions, so that students have a better idea of which ones are realistic ones to apply to.
The moderately selective stats-formula ones can publish their stats formula and past admission thresholds. This should be done by division and major when applicable (a common area where transparency is lacking, since overall school admission stats do not show how much more selective specific popular majors are). Of course, if they are confident enough that setting automatic admit criteria will not result in overenrollment, they should publish automatic admit criteria.
More selective ones with holistic or subjective admissions review can publish a grid of HS GPA or rank and test score ranges with historical admit rates for each combination. Again, a grid should be published for each division or major that admits separately.