For what it is worth, I am the employer.
I have had about 12 people resign in the past year. 3 Joined up to start a new company, 3 went to work for one competitor, 2 sought better pay, 2 had similar issues to pay (commute), and the remaining two made quality of life moves.
While only the three were real assholes about it, all twelve were technically disgruntled.
For the record, as a "nerd," I fully understand how to completely invade the privacy of my employees. I consider those actions unethical. They are entitled to be disgruntled, and I need to understand when they are unhappy and do my best to address it. Reality is that people that have a honest need to change, but value their employment handle things differently. They communicate well in advance of two weeks notice, and they provide options for both parties. They are not afraid of being treated like outsiders; they are still invested in mutual success.