Power to the People
Power Levels within the game are ridiculously high, there really is no other way of putting it when a level 10 martial artist can exceed a power level of 14000 with ease.
Based on information gathered we can safely assume that the power levels depicted in game by human made scouter tech are not running exactly the same software as those used by Friza's minions in the anime or manga but rather a modified version designed to convey power levels more closely associated with humans.
Why so Low?
It was noted in various source materials and wiki's that "normal" human power levels are significantly lower than those depicted in the primary characters. With this in mind we cannot assume that the minuscule infusion of Saian DNA would have such a marked effect that pre teen humans could suddenly exceed the massive power levels shown by Tien and Yamcha during the first encounter with Vegata and Nappa.
Humans depicted at this time ranged from a normal human level of rough Power Level of not much more than 5 to the impressive 1500 of Tien or even 1200 of Yamcha at there combative peak.
So lets look at this in another light, in order for a human in DBO to exceed human power level limitation they would have to excel well past the power levels shown by Friza's minions on Namek each of which had power enough to destroy large chunks of the planet with ease.
Clearly Humans do NOT have this level of power so we have to presume that Human made scouters and the power levels depicted within them have to have been slightly altered to better read human scaled power, after all if a human with a power level of "5" is a fit and healthy farmer working with his hands then a lazy slob playing video games in the city would be well below "0" .
Power level Zero?!?
Once again we have to presume that a power level of zero is not a non existent power level but merely an unreadable level by sayian (or shoud i say Tuffle?) standard technology.
We can also presume that this was unacceptable by the new found Ki users and more importantly Capsule Corp sales department to have the customers who were now capable of throwing energy balls and engaging in feats of superhuman strength were only registering at power levels in the range of 100 (level 1 player characters) and below.
This does make sense not only from a commercial point of view but also from a military and civilian police in terms of law enforcement and simple scaling for training purposes.
This means basically that Human scouters have been dropped down a full decimal point in order for humans to properly register there power levels. So for ease of use we can presume the following based once again on our friendly farmer.
Sayian Scouter power level: Untrained Fit Human Farmer - Power level "5" (5.0)
Human Scouter power level: Untrained Fit Human farmer - Power level "50" (50.0)
This means that Human scouters are roughly 10 times more accurate that the Sayian equivalent, or rather they depict power levels through an extra 0.1 variable.
this would mean that Goku having been read after his training with King Kai would have registered at roughly 90,000 on a modern human scouter.
This also holds true with the time travel quests as scanning Goku at the WMA shows Goku's power level well in excess of the famous "over 9000" at roughly 14000, with a Sayian scouter this would only register at no more than 1400 which as we now know would eventually be the maximum ki output of a human prior to the namek saga.
In conclusion:
We can now safely assume that human scouters are significantly different to the ones depicted the the manga and anime...
...but this does mean that we are nowhere near as powerful as we think we are.
oh well back to training after all if Krilin can cap out at 1500 (Sayian scouter during Namek saga) the little bald chap would be in excess of 15,000 on a Human Scouter.
Remember this is only a theory but then again it does make sense.
*Note All information is based on the book "its over 9000!
http://www.amazon.com/Dragon-Ball-Wo.../dp/B0092HRZCI on certain translations from various international forums and is merely a theory based on observation based within the realms of available gameplay and can be ignored should it fall outside your personal thoughts and feelings regarding your character and his/her power levels.