Errors in core supplied css file and module css files

I've noticed what I feel are errors in the system.css file and a few module css files. Noticed the errors while searching for a reason for error highlighting not working with form checkbox and radio types, http://drupal.org/node/222380. The problem is the use of 'checkboxes' and 'radios' where 'checkbox' and 'radio' should be used in the selectors.

Error examples:

.form-checkboxes, .form-radios {
  margin: 1em 0;
}

The following selector names are used in the survey and forms modules:

.form-checkbox, .form-radio {
  margin: 1em 0;
}

I'm not sure if these errors were by design or simple typos? I've tested using 'checkbox' for 'checkboxes' and radio' for 'radios' in the css files and the change does affect the theme output. I think they should be changed to match code that is being used and expected by modules. Other module css files I have checked use the correct non-plural version of the selector names.

Affected files with lines:

system.css
Lines: 98 and 101 for both 'checkboxes' and 'radios'.

Also found in the following module css files:

locale.css
Lines: 69 for 'checkboxes' and lines 73, 243, 350, 355 for 'radios'.

form.css
Lines: 553 and 1323 for 'checkboxes' and line 1082 for 'radios'.

content_types.css
Lines: 156 for 'checkboxes'.