You can also just buy pure caffeine powder and mix it with your favorite drink, or buy capsules seperately and make your own pills. Probably much more cost-effective.

And yes, from personal experience, I can attest to the fact that pure caffeine has an extremely bitter taste.

(Which begs the question, does it taste bitter because it is after all a neurotoxin and we have evolved to find those lacking in taste?)

Yes. No way they're going to spray it in their mouths, caffeine is horribly bitter. Assuming it absorbs well through the skin, this is advantageous as a delivery system because it won't go through first-pass metabolism by the liver and kidneys as anything absorbed by the gut does. Theoretically, this means that a much lower dose is necessary.