Accuracy
is, and probably will always be, a contested subject. Even the
readings on the most sensitive gauges ever made will be subject to
factors beyond anyone's control. This is why it's reasonable to
consider a margin of error every time you take a measurement,
especially when it comes to currents.
Given
that current transformers are always on the lookout for unusual
energy spikes, accuracy must be their most defining feature. They
don't have to be perfectly accurate, just accurate enough to confirm
the readings and help managers make sound decisions. However, no
one-size-fits-all transformer exists at present.