This captcha thing is a pain in the butt

Question

I tried to post a lengthy answer, and the system won't post it makes me enter a capcha. That's one of those things where they show images of smeared text to foil automatic text interpretation software. However, there are two problems with this:

1. I am already logged in, so GET OFF MY CASE!

2. I am human, but I still can't make out the letters. They are so obfuscated I can't figure them out reliably either.

With your paranoid attitude you are now making it impossible for legitimate users to do legitimate things.

LIGHTEN UP!

Here is a example where I just failed again:

The first time I clicked on the button it did nothing. I waited a few seconds and clicked again. This time it told me I got it wrong and popped up a different capcha. I entered what I thought was right and it just poofed me back to the question without having submitted my answer.

More:

I just found out that on apparently three of my tries it did post my answer. Since it didn't show me the answer, I thought it didn't get posted and kept trying again. I deleted two of them to the extent I can. The whole mess is here: Rules and guidelines for drawing good schematics

Added 5 Sep 2012:

I just got another one that real humans can't decypher either:

It rejected that input.

Is this overly aggressive system ever going to get fixed!!?

Added 26 June 2013:

Here is another one that failed:

Answer 1

I remember having the CAPTCHA once or twice on SE sites, each time when I made a couple of edits very quickly one after another. But being logged in should be sufficient to trust you, and CAPTCHAs are not necessary then. The status-bydesign tag is not a good answer.

The purpose of a CAPTCHA is twofold:

• Keep bots and other malicious users out, and
• Allow legitimate users in

There are CAPTCHAs and CAPTCHAs, and the one used by SE seems to have forgotten about the second purpose. My experience with this one is that I often have to generate several new images because they are totally illegible. I can understand that having to retype it (maybe twice?) is too much for Olin's short fuse :-).
If you need a CAPTCHA, why not use one which does not try to keep you out, like the one I use on my own site?

From time to time I reject suggested edits like this one:

This seems to from a bot, but I don't see what they're aiming for. It makes no sense and the links are also just a random sequence of letters. But recently I had this twice in a few hours time, and on the same answer. Wouldn't it be better if the CAPTCHA were used for anonymous users than for registered users who are logged in?