There is more logic on the DME / ECU than what a flash has access to. The hardware needs a base layer that starts it up similar to the BIOS on your computer, this layer has some basic logging abilities that you cannot override by design. There are also other data logs that would be cumbersome to spoof even if you could get around the base level logging.
The other side of this is that no tuner wants to be on the hook for enabling hundreds of people to commit felony fraud. That is a sure fire way to end up staring down the barrel of a ton of corporate attorneys for Toyota, BMW, etc.
