There are so many tech jobs out there... Where are the Americans?

They say that h1b holders take away American jobs. Take a look at the job sites and you see so many jobs all of which are exclusively for American citizens or green card holders.

They remain open for months. So, where are the American citizens whose jobs h1b guys have taken away?

Why are they not filling up these positions?

It is a lose - lose proposition. The truth is nobody is able to fill up these jobs....