I can give an actual example of problems I have experienced by using google maps or similar websites.
I was on a short trip to Lisbon last year and relied at first on google maps and trip advisor. On such trips, I like to discover the city walking or using public transport and also like to visit some places off the beaten path. I wanted to visit a botanical garden. My hotel was not in the city itself, but 10km to the west.
While searching for botanical gardens, google maps would not give me the famous one in the city center by only gardens closer to my hotel. Naively, I thought the one I looked for was in the list, and proceeded to visit the largest one, which was closed for renovations. Only when I was there, and therefore closer to the city center, did it show me the one I was looking for, which was open but still quite afar. It also then showed me further botanical gardens, much farther away and as far as I can tell not open to the general public.
Back to the hotel, it showed me the one which was closed and not the one in the city center. The usual workarounds did not help.
Tripadvisor was markedly worse. All it apparently wanted me to do was to book a tour by a city guide. Except that the tours were organized from tourist hotels in the city center (so not mine) and only bookable the day after tomorrow. And that I did not want a tour at all, of course. And I could not find out how to use public transport.
I had a rental car (even if I also wanted to use public transport), and google maps or apple maps, while proving to be invaluable in main roads, were very frustrating when traffic was congested as they were not able to suggest anything else than using the car to add to the jam.
On the second day, I found out that there is a non-commercial site for travelers:
http://wikitravel.org This proved to be a much better choice, explained how to use public transport and where to find actual interesting places.
http://openstreetmap.org , of which I am a contributor, also proved much more useful when visiting the terrain on foot.
In that trip I also discovered a peculiarity of google apps on the iPad (I used and iPad for the trip). One cannot escape google spying powers on Android (except by heavily hacking the device), but one can on the iPad and normally I do not use a google account at all. During part of the trip I had to (for unrelated reasons, someone send me a google spreadsheet). This is where I found out that google apps circumvent iOS protections and make it sure that you are logged in all google apps at once. So if I wanted to use the spreadsheet, I would also be logged in when using the map application, or any other application and the browser. And then, I also got different answers to my searches.
I suppose that most people would not notice. Google maps pretends it is most useful when driving to work. Maybe it is, but I don't need a map to drive to work, I know my way around. OTOH, one expects a map to be useful in places he or she does not know. Except that if it only presents you biased info in places you do not know, you are not likely to ever find out.
There is a further peculiarity of all electronic maps that you are not likely to notice. In a next post, if you are interested.