SELECT with arbitrary input and buttons with values separated from text is possible?

Hello. I designs some statistic program for our company, with HTML
frontend. And i found
some unlogical things in HTML standarts, so i want to know why some things
missed in HTML.

1. Buttons. Why the value of a button control is equal text on the button?
I can have 100 button
with text "Submit" in different pages of my app, but for parsing $_POST
array in PHP i want different
names, that can hint me what action exactly PHP script must perform. Why
it's not possible
to write <input type=submit name=action_but value=add_user text=submit> ?
Now i use union of name and value in name, like <input type=submit
name=action_but_add_user text=submit>,
and i am compelled to use additional searching by pattern and parsing
undefined $_POST key, instead of using
simple check like if ($_POST['action_but']=='add_user').

2. Why HTML standart not describes combo box with possibility of any user
input. I know that
exists number of suggest JavaScript scripts, that extends functionality of
generic input, but
some users may disable JS. Is it so hard to do like
<select name=group_type allowunlisted>
<option value=one>First</option>
<option value=two>Second</option>
</select>
and give to user ability to select value or enter his own value?