It is really not much more complicated than this:

Google Pays Apple $1 Billion A Year To Be Default Search Provider On iOS.

$1 Billion a year to be Apple’s search default.  So, I guess there is money to be made in search (and retrieval)…

…if you are Apple.

Google Pays Apple $1 Billion A Year To Be Default Search Provider On iOS [Report] | Cult of Mac.