This kind of statements are useless without specifying what kind of data was wrong and where.

In my city (Kraków, Poland) road data, bicycle infrastructure, pedestrian infrastructure is extremely well mapped. Shops? Probably about 3% of them are mapped.

China? You can find entire cities not mapped at all (for multiple reasons, starting from fact that mapping in China is illegal without permission from government).

If you spot any wrong data (or very, very important missing data) - please report it https://wiki.openstreetmap.org/wiki/Notes#Adding_notes

Or even better, map it if you want - feel free to ask for help, for example here (or elsewhere, see https://wiki.openstreetmap.org/wiki/Contact_channels https://community.osm.be/ )