The political leaning quiz is extremely biased though. Its basically all questions like "should stuff benefits humans or corporations", which doesn't represent what both sides actually thinks.

The questions look like they're taken directly from politicalcompass.org. Its not exactly scientific, but there are 20 years of results floating around to compare with since it was a popular site on the early internet.

That's essentially what is boils down to, though. If a policy would benefit corporations, the GOP supports it. If a policy would benefit citizens, the GOP is against it.