Drunk Driving, Part II

A week ago, I mentioned that a friend's friend had been killed by a drunk driver.  That friend was a student in a class I teach, and that night, another student was hit by a drunk driver on her way home.  She is okay.

My question is this: Why is DWI a separate law, under a separate section of the code.  Anybody who's driving drunk knows that:
A) People, made of flesh and bone, are squishey and easily damaged by heavy objects moving quickly.
B) Cars easily fit the definition of such heavy objects, so it is crucial to not hit people with them
C) While drunk, it is much harder to control your own two feet, let alone the aforementioned heavy object.

Ergo, driving drunk places others in imminent risk of bodily harm.  Why then do we have a separate code for it, with lighter penalties, when the law of reckless endangerment would serve just fine:

Texas Penal Code, Ch. 5, Sec. 22.05.  DEADLY CONDUCT.  (a)  A person commits an offense if he recklessly engages in conduct that places another in imminent danger of serious bodily injury.

... 

An offense under Subsection (a) is a Class A misdemeanor 

Which carries this penalty:

Sec. 12.21.  CLASS A MISDEMEANOR.  An individual adjudged guilty of a Class A misdemeanor shall be punished by:

(1)  a fine not to exceed $4,000;

(2)  confinement in jail for a term not to exceed one year; or

(3)  both such fine and confinement.

Compare to:

Sec. 49.04.  DRIVING WHILE INTOXICATED.  (a)  A person commits an offense if the person is intoxicated while operating a motor vehicle in a public place. (b)  Except as provided by Subsection (c) and Section 49.09, an offense under this section is a Class B misdemeanor, with a minimum term of confinement of 72 hours.

[NB, absent the special code for DWI, it might be hard to prosecute, so we would be well served to make DWI ipso facto reckless endangerment, the same way pointing a gun at someone is.]