Well, that's kinda the point, though, isn't it? If you don't have a degree from Yale that vouches for your electronics expertise, well someone is going to need to vouch for you... and that someone will be somebody already in the union. That's pretty much why they work. People know each other. They work with each other. They tell you honestly whether dude is right for X, Y, or Z job. Or if he isn't. So the part about "knowing someone, so you can get in" is just how life was before colleges came around and began passing out "entry tickets" for $35k a piece. You had to know someone, and that someone had to vouch for you. "Take a chance on this kid. He's dumb now, but he learns fast, and works hard."
Really? I'm not sure I follow. To get a job you generally need someone to vouch for you. A friend introduces you to his Union boss, or a university gives you a piece of paper. Either way, that's your entry ticket to the job market. Unless you just go out totally on your own and build something new that every just must have. But those types of ideas and people are rare, indeed.