That's understandable, a lot of exploit seekers use those features to find exploits e.g. "powered by [cms with known exploit]", Google (and Bing) are definitely

That's understandable, a lot of exploit seekers use those features to find exploits e.g. "powered by [cms with known exploit]", Google (and Bing) are definitely are more prone to showing you a captcha for those searches, especially if you're looking beyond the first page.