What - you expect them to admit they hire the mediocre? Anyway, the labor market is a market like any other - the consumer, in this case the employer, wants to get the best product (labor) at the cheapest price (salary). This isn't complicated.
Looking at this a little more deeply, the biggest issue is American labor is getting underpriced. What's causing that? Well, for starters there's the cost of an American education. The employee is looking at that as an investment and they expect a good ROI.
The second is inflated lifestyle expectations. That's been a big problem in America since the 90s. People aren't just living beyond their means, they're living well beyond their means - and just like the billionaires, they want more.
The result is we have recent college graduates expecting nice six-figure salaries. It's easy to offshore that. The growing trend now is to offshore to South America so you don't have to deal with the time zone shifts. You always have to remember there's someone a wee bit hungrier than you who is willing to work a wee bit more for a bit less. That's the person your employer wants.
This is what happens when you treat people like commodities, and you worship the market and money as your lord and savior.