I have added from pictures to missing places into Google. For me, the tit for tat is to help other travellers to find interesting places, to not get lost or to know what to expect when in a foreign country/city.
But, I always contribute similar content to Wikipedia/Wikicommons. Because I see that as a more fitting philosophy for sharing knowledge. The type of information and the format is not the same, thou.
Google is just practical. It is frustrating to plan a visit to a museum in a city that I will spend one day to find out that has been closed for half a year.
So, I agree as I have my own self-doubts about giving things for free to Google when they are going to use that data to send me or others more targeted advertisements.