That's not the way universal background checks work in the world of gun control.
In the common vision of background checks, a federally licensed dealer is always part of the process and it must be done in person at the dealer's place of business. You and a potential buyer agree on a sale; you take the gun to the dealer, who enters it into their inventory. The purchaser then completes the required ATF Form 4473 and the dealer makes the NICS inquiry. Upon receiving a "Proceed" decision, the dealer then delivers the gun to the buyer and collects the agreed-upon price plus a transfer fee.
Neither the FBI's NICS system nor the various state systems are set up to handle inquiries from private citizens. Normally, inquiries to background check systems are limited to bona fide law enforcement officers; the addition of the federally licensed dealers took a few years to implement.
In addition, there is a huge gray area involving what constitutes a "transfer." You may think it's the sale or gift of a firearm or a similar commercial transaction.
However, in the Bipartisan Background Check Act of 2019, transfers included loaning a rifle to a friend for a hunting trip without any expectation of any compensation at all. In fact, even handing a gun to another person at a shooting range is a transfer. So is loaning a gun to a person who is concerned about a stalker or jealous ex.
For the sake of argument, let's suppose that you are like most people in states that have enacted universal background checks, you pay no attention to them. As long as the gun you sell to a buddy was originally purchased before the law was passed how is anyone going to prove that you sold it to your buddy after the law was passed instead of beforehand?
Nevada passed a much ballyhooed universal background check law in 2019. There isn't a sheriff in the state that will enforce it - because it literally can't be enforced.
And how about the feasibility of registration? After all, there is a popular fantasy that if a registration law is passed, everyone will dutifully line up, eager to comply.
In 2013, New York passed the SAFE Act, requiring owners of certain types of firearm to register them with the state police by April 2014.
After losing a Freedom of Information Act lawsuit in 2016, the NYSP was compelled to release compliance data. At the time, it was estimated that anywhere from 250,000 to a million of these guns were owned by residents of New York state. Slightly more than 44.000 were registered. Depending on whose estimate you believed, the compliance rate was anywhere from less than 18% to perhaps less than 5% - in New York state, which is famous for gun control.
What do you think compliance is going to look like in Idaho? Maine? Texas?
A lot of people looking at national legislation forget another small, but important, problem: the federal government cannot compel a state or any state official to enforce a federal law. They can't prevent federal officers from enforcing the law, but that cannot be compelled to supply any assistance at all.
Some food for thought: In February 2019, Marist conducted a poll commission by NPR and the PBS Newshour. It was a poll to measure support for various gun control measures.
The survey was nothing special except for the very last question. Survey participants were asked if, based on what they had read or heard, the per capita gun murder rate over the past 25 years in the U.S. had gone up, gone down, or stayed about the same?
59% of those responding said it had gone up, 23% said it had stayed about the same.
According to the CDC, the per capita gun murder rate in the 25 years from 1994 to 2018 plunged more than 36%.
Why do you think 82% of respondents believed something that was demonstrably false? Could it be the same reason gun owners don't connect the dots between background checks and registration or are surprised to learn that fewer people are ending their lives with guns and more are dying at the end of a belt, extension cord, or rope?
Maybe somebody hasn't been telling them the truth.