On the PC they're offering a free service that costs money to run, i.e. they have to use ads. On the DS they're paid by Nintendo.
Gamefreak: You forgot how critical recon was in TA. Few other games implement so many techs and countertechs- radars, radar jammers/stealth, sonars, sonar jammers, optical cloaking, nukes, anti-nukes, etc. Setting up areas patrolled by scout and fighter planes with artillery support, having units generally see less than they can shoot (I once had 20 Goliaths destroyed by one GAAT because I couldn't get it into my FOV), Big Berthas... I think there weren't many games this close to large scale warfare.