I suppose that's sometimes true. However, some people in certain situations might receive unsolicited job offers, without ever even creating a resume or submitting an application, right?
The point I was trying to make is that, I'd encourage young people to follow-up after sending out a resume. It will help you gain 'chops' for future calling/prospecting that may be required. Also, it's professional to follow-up with a phone call after sending an email to someone you've never met or spoken to before.
I get a lot of unsolicited resumes sent my way. Hardly anyone ever calls to follow-up. My thought is, I'm a busy person, and if the person really truly wants to work with me, they won't give up. I want to see persistence.
I bet that Amazon, Google, Facebook and Microsoft all have very well-thought-out recruiting programs. I'd imagine that young college grad's could be hired for a lower salary than older, more seasoned software engineers. Those large companies are probably more flexible with young recruits. Everything in life is a trade-off. Why would those companies "shower" kids fresh out of college with job offers? I'd venture to guess that they are interested in hiring them because it's cheaper than hiring someone else with more experience. Or maybe that's how it is in the software job market. But as I see so many Americans out of work, expecting someone to 'create jobs' for them, I think it's important to highlight what it takes to get a job that you want. I'd consider your example of software engineers being "showered with job offers" as an exception to the rule. Most people have to actively pursue what they want in life. Plus, in 25 years you don't want to be one of those people on TV begging the government to 'create jobs' for you! So my advice is to learn how to get what you want by asking.