That's quite a stretch ... going from web scraping email
contents to holding up cash registers. How about the
analogy of not coming to a complete stop at a stop sign
instead? Regardless of how you like your analogies, if the
scraper uses the public interface provided by said provider,
then how can it be illegal? Whether you use that interface
through a browser or a web bot shouldn't matter as long as
that interface is publically available. I can use the front
door to a public library if the library is open. Can i not
also teleport into the library lobby as long as it is open
to the public? What? You can't teleport? ;)