Technology develops. The critical principle is that, officially at least, access to my data currently requires my active consent at some point in the process - having a compulsory microchip on uncontrollable permasend materially changes that dynamic.
If the chips are the same as those used in pets they aren't on permasend.
They have to be read by an interrogator which fires a pulse of RF at them to wake them up.
They're awake long enough to be read and then become inert again.
They have no source of power built in so cannot permasend.
The interrogator has to be within millimetres of the chip for it to work.
In my last job we used similar sorts of chips to identify chip and pin machines in petrol stations. The scanner had to be touching the chip to make it work.