Is that not a problem? According to an earlier post (no pun intended!) the purple paint must be “placed so that the bottom of the mark is not less than 3 feet from the ground or more than 5 feet from the ground.“ so if it goes right down to the ground it's not compliant.
Probably not serious, but you wouldn't want an issue on a technicality.
tl;dr: Posts painted entirely purple are more than is required.
Texas Penal Code § 30.05. Criminal Trespass
Sec 2 (D) the placement of identifying purple paint marks on trees or posts on the property, provided that the marks are:
(ii) placed so that the bottom of the mark is not less than three feet from the ground or more than five feet from the ground; and
.... this seems quite clear that the mark needs to end 3 to 5 feet above the ground
.... a post painted all the way to the ground is just a purple post, not a purple-marked post
... at least it's an upgrade on a rusty old pipe
Doesn't the "not less than" part mean that you can paint it more if you so desire