Re: "Surly we can come up with a similar device with replaceable strips?"
My blood glucose meter uses a rigid(ish) plastic strip which plugs into - and activates - the meter electronics. The end is held onto a pinprick spot of blood and capillary action takes a tiny sample of the blood along the strip to where the sensor (whatever that is) is. Electrical contacts from the device permit the magic to be done.
It would seem that a similar system could perhaps encapsulate the sensor strip on the pregnancy test paper and hold the stripes under a sensor - but as pointed out elsewhere it's not obvious where the market would be, other than in a doctor's surgery or for someone trying to get pregnant and testing regularly.
I suspect though that the most common use case might be - oh no, am I? Oh, thank heavens, no... (though as a married bloke whose kids came along with the package I am totally unqualified to speculate on that). And if someone is likely to find themselves having to purchase tests for that reason on a regular basis, they've perhaps got more immediate issues than worrying about wasting plastic - and perhaps they're not likely to consider multiple use testers.
Because, hey, hundreds of times nothing happened at all, right?