It’s because you’re not just an employee.

Jared Kushner is Trump’s trusted senior advisor. His areas of responsibility aren’t defined, but are considered comparable to those of senior advisors Steve Bannen and Reince Priebus. Possibly added together.
Kushner is head the White House Office of American Innovation, tasked with restructuring the government to work the way private businesses are built. He’s also tasked with domestic issues like Veterans’ Affairs, workforce development and the opioid addiction crisis.
In February, the Washington Post reported that:
Although Kushner, 36, has no traditional foreign policy experience, he has become the primary point of contact for presidents, ministers and ambassadors from more than two dozen countries, helping lay the groundwork for agreements, according to U.S. and foreign officials with knowledge of the contacts. He has had extensive talks with many of these diplomats, including in Europe, the Middle East and the Asia-Pacific region, the officials said.
The Post forgot to mention Mexico. Right after he manages peace in the Middle-East.
Speaking of which, Kushner is reportedly the peacemaker between warring factions in the White House, a job that nobody thinks is trivial.
The Washington Post reports that Kushner has met with Russian diplomats many, many more times than he disclosed on his security clearance applications.
This isn’t a small thing. He discussed unknown issues with the United States’ chief adversary. Kushner did this in the middle of investigations into elections that benefited Trump and, of course, Kushner. And after Kushner didn’t disclose his first round of meetings, Kushner held more meetings he also didn’t disclose, despite being warned in writing (I presume) that he was supposed to let the authorities know what he was doing, especially when contacting one of America’s largest and most savvy adversaries.
For most people whose work requires high levels of public trust, this kind of allegation would mean his clearance would be suspended immediately, and the government would start an investigation into the charges. If Kushner did lie, and it was deliberate, that’s worse. And if he lied about issues of substance, that would be even worse. Right now, and ordinary employee would be looking at a potential felony, and possibly worse, depending on what the Russian discussions were about.
But Kushner is also Trump’s son-in-law, and while he could be suspended from any of his other executive positions, the Office of Government Ethics can’t really suggest Trump relieve Kushner of those duties.
That’s the problem with being a relative. It’s simply impossible for Kushner to receive equal treatment under the law. That reason — and because people love hiring relatives for lucrative positions they don’t being to qualify for — is the reason it’s illegal.
Trump and Kushner swore it wouldn’t be a problem. Except that now it is, and they’re not doing anything to help.

