You are correct. I mistyped when I said 'seize'. Search, I can do that if I choose...... should you not allw me, you then have to leave or I will have you arrested for criminal trespass. The Fourth Amendment only protects against searches and seizures conducted by the government or pursuant to governmental direction. Surveillance and investigatory actions taken by strictly private persons, such as private investigators, suspicious spouses, or nosey neighbors, are not governed by the Fourth Amendment. Read more here: http://criminal.findlaw.com/criminal...t-applies.html
Further reading: In its 1920 decision in Burdeau vs. McDowell, the U.S. Supreme Court held that the fourth amendment is not applicable to searches by private parties.
You are partly right, and partly wrong. According to the source that you linked yourself, employers can only search some things without a warrant. You can search your employees' computers, desk, workspace, company-owned vehicle, and such, because there is not reasonable expectation of privacy there. There is a reasonable expectation of privacy for a person's body, purse, briefcase, and personal vehicle.
You need a warrant or at the least a reasonable basis for suspicion that an illegal act is being committed against you in order to search those things. Carrying a legal weapon in a personal vehicle is not an illegal act, and is not causing you harm as an employer. The only way around it is if you make agreeing to searches of personal property a condition of employment. That is usually only done in places where there is a likelihood of employees stealing valuable or sensitive property or documents/files.
The fourth amendment may apply to the government, but that doesn't give you the right to go breaking into people's cars unless they have signed an agreement with you that allows you to search it. Breaking into a locked personal vehicle is very much a criminal act, regardless of where it is parked at. Try it and see what happens. Just because you wish you can do whatever you want doesn't give you the right to commit a crime against another person.
Surveillance of your employess is also your right, but even there you have limits. I don't think anyone is going to go for you having cameras in a bathroom stall or locker room, because of that same old pesky "reasonable expectation of privacy" that you don't seem to agree with.
Again, explain to me how an employee having a legal firearm locked up in their car is taking away your rights, or harming you in any way. It seems to me that it is much more about controlling other people than rights with you. You seem to be confusing employment with slavery. You don't own your employees, and you don't have the right to dictate their lives. In the early 1800s, you could have done all those things you want to to your "employees." But you can't now, sorry.