Samples are too complex

[idish]

Play billing sample (the trivial drive kotlin one, not sure about the JAVA one as I haven't followed this one), is way too complex to study from and to implement in own app. There's a massive use of classes, flows, livedata objects and generally very much coding that isn't self-contained. All of that makes it very hard to implement accordingly in own app. The example app is too specific, and is over-complicated in many manners in my opinion.