I think we should just roll some kind of standardized test into your Junior year. Instead of it being this external expensive thing, everyone who wants to go to college can just take a half year preparation course in your Junior year and take the test at the end. We don't need this to be external. We already do a lot of standardized tests to measure student performance. This fixes the GPA problem between schools and the uncomparability of those numbers.
The issue with standardized testing that's just rolled into coursework is that it'll further incentivize teachers to teach to the test. In my opinion it could also disadvantage schools which don't have education in the highest of mind. Basically running as a daycare center in some sections.
What states are those? No schools that I know of locally have SAT prep as a school course or use the SAT as their standardized tests. It is good that some schools are already moving this way. I think it makes sense to have just one standardized test that can be used for admission and also tracking progress of schools and states.
SAT: Colorado, Connecticut, Delaware, DC, Idaho, Illinois, Maine, Michigan, New Hampshire, Ohio, Oklahoma, Rhode Island, South Carolina, Tennessee, West Virginia.
ACT: Alabama, Arkansas, Hawaii, Kentucky, Louisiana, Mississippi, Missouri, Nebraska, Montana, Nevada, North Carolina, North Dakota, Utah, Wisconsin, Wyoming.
Also, the implementation of SAT prep is spotty at best. As with most things, whether the schools have test prep is pretty reliant on how well funded the individual district is. At least that's my experience.
One of the drivers for Colorado moving to the SAT from the ACT was the amount of free SAT prep courses online. SAT partnered with Khan Academy to offer a lot of test prep and practice tests online for free.
In Colorado all high school Juniors take the SAT in April for free. I think they have to pay to add the writing section but most universities have removed the writing requirement.