It's not included with Uber, they just don't get a tip unless you hand them cash. With Lyft you have the option to tip but it's not required. Lyft drivers get to keep 100% of the tips too. I always tip on airport runs, even if I take a taxi, unless they long haul me.

Edit, you guys can quote Uber all you want. Tips are not included with Uber or Lyft. It's just that Lyft gives you the option to tip within the app. I'm not saying anyone has to tip BTW but don't delude yourselves into thinking "tips are included." They make $1/mile now in LA which is not much money when you pay for gas, depreciation, maintenance and dead mile to your next fare.