Why not captcha on comments by default?

Because captcha doesn’t work. It’s surprisingly easy to crack, it’s not accessible for visitors with limitations, it’s not friendly for non-english speakers, and the list goes on.

Read what Otto says here:
https://www.ads-software.com/support/topic/which-is-the-best-captcha-plugin?replies=19

Use a plugin if you must, but Akismet, Cookies for Comments, WP Hashcash, Bad Behavior and a good firewall on your server is a better method.

Yup, @ipstenu speaks the truth

A good combination of plugins, and there is no need for captcha. Why alienate anyone?

I don’t even see spam anymore using the combination mentioned above.

The problem is that WordPress-spam is made profitable by the lack of spam-protection in the comments.

Newbies doesn’t know that such plugins exist.

Akismet is included in WP, it’s just turned off.

If you have more problems, you have to *gasp* do a little work and learn. Google “Why does my blog get spam?” and WORDPRESS has the second hit ?? So yes, there’s an expectation that you, the user, are going to do YOUR job and learn. If not, well, you get what you get.

There’s captcha on blogspot, and just as much spam (and far more annoyed users).

As I said, I dont have a problem with this but thousands of other people have problems.

Turning Akismet on will be more than enough for many blogs. Many newer sites won’t have that much spam early on but as it grows, that’s when you can decide to use additional tools.

Regardless, WP provides a solid framework but at the end of the day, this is your site. I’m just glad I have so many tools at my disposal.

The ‘you’ was meant to be generic.

Thousands of other people aren’t learning how to run a blog. It’s work. It takes effort. Same as learning anything else (like driving a car – remember the first time you had a flat in the middle of nowhere?). You learn ??