answer:People can write programs that use a web site, they don’t want that, it’s a site designed for individual users. For example, I use a site where I look up property histories – deeds, mortgages, etc. If they let bots use it, they would programmatically go through the data property by property and vacuum up the county database. The system would slow to a crawl, and become unusable for everyone else. Or you could write a program that tried to guess user names and password to break into accounts. By placing a captcha on the page that can’t be completed programmatically, they assure the site is used by individuals, not abused by programmers. My apologies if you knew this already. Why Google specifically is challenging you, I don’t know. I assume someone is abusing the site.