In Germany there is a database with official and up to date (delay of under 5 minutes, probably more like 1 minute) database with gas prices. All gas stations have to report their prices to that database.
It would be great if Waze would use that database. The information is free and many apps that use it exist (https://play.google.com/store/apps/details?id=de.mobilesoftwareag.clevertanken , https://play.google.com/store/apps/details?id=de.msg)
More details here: https://www.bundeskartellamt.de/DE/Wirtschaftsbereiche/Mineral%C3%B6l/MTS-Kraftstoffe/mtskraftstoffe_node.html

Similar projects might exist in other countries too. If any of the users know about similar databases elsewhere, please comment here.

Thank you!