Methinks, mayhaps, you expect too much from our beloved intertubes (and transcribers in general as well). I always take online tabs/sheet music (and even professionally released transcriptions sold at a premium) as mere guidelines that are useful in possibly pointing me in the right direction of how something is played... but never fully accurate.
I have much more success at being accurate learning things by ear. If something isn't sitting right then I'll see what is available as far as transcriptions and they may (or may not) give me some ideas as to what I may be doing wrong.
What is REALLY helpful to me is live recordings though because generally the performance is raw so you can hear what is being played as opposed to what has been edited/mixed into a dull roar. Video of a live performance can sometimes give a clue to where my hands should be. I have now discovered a neato little tool in GR5 (the Tape Deck thingie) that allows me to slow down recordings easily without changing pitch so I can pluck out notes of very fast solos which is cool.
Then I can go back with all my new found data input and reprocess what I'm hearing and cobble together a better representation of what is going on.
The one thing to realize too is that often times different renditions are being transcribed or there are alternate tunings in play which screw up the transcriber.
Many online transcriptions are contributed to sites by... well I won't say amateurs but they are just uploading their interpretations for whatever reason (which is why the sites that publish them have rating systems). The pro stuff you buy in the music store is obvioulsy much more accurate but I gave up on that stuff ages ago because really there is still a lot of innacuracy as far as HOW stuff is played (because unless the actual artist is there to show them exactly how they played it the trascriber will interpretet it how THEY would paly it) and those darned things are bleeding expensive (also it's paper which is a PITA to lug around all the time).
Obviously piano leaves a lot less up to interpretation than guitar (you can't play the same exact note in multiple places) but on paper there can be lots of variables based on the human producing the paper.
Yanno?