Uber Will Charge $15 to Return Your Lost BagIt's as much about keeping drivers as it is improving the bottom line.

The next time you take an Uber car across town, be thorough when you check the seat for your belongings -- it could prove costly to leave something behind.

Uber has quietlyupdatedits policies to let drivers charge a $15 fee when they successfully return a lost item. The policy only affects Boston and Chicago for now, but Uber tells us it will apply across the U.S. by the end of August.

It may sound like a stiff penalty, but Uber stresses that this is to "compensate [drivers] for their time." They no longer have to hope you'll strike an informal deal to pay them for their trouble. And for Uber, covering that time off matters more than you might think.

The ridesharing outfit has faced longstanding complaints that itdoesn't pay drivers enough, and efforts likesupport for tipsonly solve part of the problem. Drivers have argued that they often have to takede factopay cuts for factors that are out of their control, whether it's returning a phone or trying to find an obscure pickup spot. This still might not be enough (it could be costly if the driver is across town), but it'll at least soften the blow.

Lyft doesn't have a lost item fee as of this writing, but it encourages you to tip the driver and doesn't leave drivers empty-handed. However, Uber's move could prompt a change if it lures drivers who've had too many forgetful customers. As it is, this might have an indirect benefit whether or not you remember your gear. The more likely drivers are to stay on, the more likely it is that you'll get an experienced driver who knows how to treat you well.