TuxDave
Lifer
Cable/TelCo: No collusion. Simply matching the prices of other companies without any actual agreements or contracts between companies is not illegal. Also, this was attempted in Bell Atlantic Corp. v. Twombly and the court found that there was not even enough evidence to survive a summary judgment.
Wireless Providers: See above. Twombly is pretty much going to be in play here too.
Airlines: Again, there is no evidence of collusion.
The DOJ is going after Apple because Apple pressured horizontal competitors into contractual agreements which fixed the prices of e-books. Only in this case is there the requisite collusion to invoke antitrust laws. Right now, this looks like a slam dunk case for the DOJ and is hardly a "waste" of resources.
ZV
I don't know how much pressuring Apple needed since the publishers were dying to find a way to raise prices.