Do you block Google trackers aggressively? reCAPTCHA uses that very heavily: if you allow all of their stuff and they track you across the web, you'll have to basically never do more than click the button. On the other hand, if you take your privacy seriously and are aggressive about tracker blocking, you'll have a pretty awful time.

I imagine hCaptcha doesn't have enough trackers sprinkled around the web to use those as signals for this.