Not only was eBay v. Bidder's Edge technically after Google existed, not before, more critically the slippery-slope interpretation of California trespass to chattels law the District Court relied on in it was considered and rejected by the California Supreme Court in Intel v. Hamidi (2003), and similar logic applied to other states trespass to chattels laws have been rejected by other courts since; eBay v. Bidder's Edge was an early aberration in the application of the law, not something that established or reflected a lasting norm.
The point is, robots.txt was definitely a thing that people expected to be respected before and during google's early existence. This Kagi claim seems to be at least partially false:
> Google built its index by crawling the open web before robots.txt was a widespread norm, often over publishers’ objections.