Uber Technologies Inc [UBER.UL] will, for the first time, allow drivers to collect tips through the Uber smartphone app, the company said on Tuesday, part of a broader effort to improve its often-contentious relationship with its drivers. Uber has for years opposed adding a tipping feature to the app, which upset drivers who have argued that tips would help compensate for decreasing wages. Beginning on Tuesday, drivers in Houston, Minneapolis and Seattle can collect tips. The feature will be available to all drivers by the end of July, Uber said. Tipping is part of a broader set of features San Francisco-based Uber rolled out on Tuesday, which also includes paying drivers while they wait for passengers, as the company begins a months-long push to improve working conditions for drivers.