@sim The formality is a demonstration of an understanding. People worth working for understand these simple protocols are an assurance to each other. Some may not hold up their bargain, but the ones that won't even offer the handshake are bad news.
Neal Stephenson wrote in Cryptonomicon:
“This "sir, yes sir" business, which would probably sound like horseshit to any civilian in his right mind, makes sense to Shaftoe and to the officers in a deep and important way. Like a lot of others, Shaftoe had trouble with military etiquette at first. He soaked up quite a bit of it growing up in a military family, but living the life was a different matter. Having now experienced all the phases of military existence except for the terminal ones (violent death, court-martial, retirement), he has come to understand the culture for what it is: a system of etiquette within which it becomes possible for groups of men to live together for years, travel to the ends of the earth, and do all kinds of incredibly weird shit without killing each other or completely losing their minds in the process. The extreme formality with which he addresses these officers carries an important subtext: your problem, sir, is deciding what you want me to do, and my problem, sir, is doing it. My gung-ho posture says that once you give the order I'm not going to bother you with any of the details--and your half of the bargain is you had better stay on your side of the line, sir, and not bother me with any of the chickenshit politics that you have to deal with for a living. The implied responsibility placed upon the officer's shoulders by the subordinate's unhesitating willingness to follow orders is a withering burden to any officer with half a brain, and Shaftoe has more than once seen seasoned noncoms reduce green lieutenants to quivering blobs simply by standing before them and agreeing, cheerfully, to carry out their orders.”
It may not be military protocol involved, but this gives an idea of how working etiquette has implications beyond just the action itself.
Shaking hands with a firm grip and a confident eye is an indication to them that you're going to play with the team and get your stuff done and that you expect them to do theirs.
Whether they're honest enough to hold up their end of the bargain has other ways of being ascertained, but if this isn't present it's a bad sign.
@Locksmith @LukeAlmighty @fluffy @nerdman