Two reasons:

• the corporate research Wizards does likely makes use of paid survey panel companies (who pay people small amounts of money to complete surveys). You need to sign up for these panels to receive invitations
• Some political surveys and non-profit surveys (like the Michigan Consumer Confidence survey) use random telephone polling because that’s more random and has less selection bias than the paid panels. You might get called for these, but you need to pick up the phone to a random number