why wants google reCAPTCHA to include a Javascript in your website?

I was wondering why to use reCAPTCHA requires willing users of this "free service" toinclude a javascript from the server of google.Including a foreign javascript, that is javascript file like the reCAPTCHA, would haveserious security risk for us users. Google could at will send evil code in the javascript.This code being executed in the context of the our website has evey chance to stealand spy all the sensitive data the user enters in the website form. So I wonder how google arguments for the safety of their service if we mustassume that we give up all confidentiality of our website product by including their javascript?why is there spying with reCAPTCHA? Does google indeed want to spy? and if not, why is there no NON-JAVASCRIPT reCAPTCHAwith would protect us user? -- You received this message because you are subscribed to the Google Groups "reCAPTCHA" group. To unsubscribe from this group and stop receiving emails from it, send an email to recaptcha+unsubscribe@googlegroups.com. To post to this group, send email to recaptcha@googlegroups.com. Visit this group at http://bit.ly/1dkFnYd. For more options, visit http://bit.ly/P65DvS.