Some businesses are able to prove a job-related business necessity for IQ tests, and do require applicants to take those tests for certain positions. Most businesses can't show a business necessity for any positions, and so don't require IQ tests.
Your average company with < 100 employees almost certainly CANNOT have collected this kind of data. And larger companies will have trouble putting large groups through an IQ test with no apparent purpose, and so are unlikely to have ever collected the data needed to attempt to make the case. The practical effect is that such tests are usually illegal to use. Even though we know that they are very often useful.
And the thing is, that it's very difficult to show that IQ (as measured by an IQ test) is relevant to a specific job versus something like experience, education, etc., because "IQ" is a made up number that doesn't actually test intelligence or problem-solving abilities.
Businesses test applicants all the time. But instead of a useless IQ test, they test job-specific performance through things like coding tests, draft patents or legal documents, etc.
You need to demonstrate that the test is consistent with a business necessity. If you have a large enough people who have taken the test, and enough data on how they perform, you can make that demonstration. You've got the data, and it is enough to cover the military despite people like you who think that it "doesn't actually test intelligence or problem-solving abilities." Because, whatever it actually tests, it predicts real world performance well enough to pass legal muster.
The US military is the only organization that I'm aware of which has an IQ test with enough data that they can pass legal muster. Very specifically I'm talking about the AFQT, which is the core of the ASVAB. See https://www.military.com/join-armed-forces/asvab details on the ASVP. And see https://asvabmilitarytest.com/asvab-compared-other-iq-tests to see that it really is an IQ test to tell if you're smart enough to be in the military. And not just whether you can join, but which jobs inside of the military they will allow you to pursue.
The military has documented that this is an effective way to find people who can do things like fill out paperwork properly, and follow orders in the field. The reason why other businesses can't do the same is not because the test is useless, but because they don't have the data to demonstrate how useful the test actually is.
If they can show a business necessity, they don't need to show that the IQ test actually predicts job performance.
Notably, the army's test is not an IQ test. It is an aptitude test which is a very different thing. An aptitude test specific things are that directly and strongly related to the job (or jobs) for which the applicant is applying.