Why do horizontal matrices look different than multistory matrices?

Question

This isn't necessarily a problem, but I wonder about it every time it occurs in my writing.

Horizontal matrices (or single row matrices) have thinner brackets and are differently put out than other matrices. Even Vertical matrices don't have this uniqueness.

Best shown with an example.

\documentclass[10pt,norsk, fleqn]{article}
\usepackage[a4paper, margin=1.2cm,includeheadfoot]{geometry}
\usepackage{amsmath}

\begin{document}
$\begin{aligned}
    \vec{x}\ '(t)   &= \textbf{A}\vec{x}(t) + \textbf{B}\vec{u}(t)\\
    \vec{y}(t)      &= \textbf{C}\vec{x}(t) + \textbf{D}\vec{u}(t)
\end{aligned}\ \ \ \to\ \ \ 
\begin{aligned}
    \dot{\textbf{x}} & = \begin{bmatrix}
        2&1&1\\3&-2&-2\\1&1&2
    \end{bmatrix}\vec{x} + 
    \begin{bmatrix}
        2\\1\\2
    \end{bmatrix}\vec{u}\\
    \vec{y} & = \begin{bmatrix}0&-1&-1\end{bmatrix}\vec{x}
\end{aligned}$
\end{document}

Answer 1

The bvector environment was specifically set up to match 1 row to 3 row matrices.

\documentclass[10pt,norsk, fleqn]{article}
\usepackage[a4paper, margin=1.2cm,includeheadfoot]{geometry}
\usepackage{mathtools}

\newlength{\brackoff}
\sbox0{$\begin{bmatrix}\strut\end{bmatrix}$}
\sbox1{$\begin{bmatrix}\strut\\\strut\\\strut\end{bmatrix}$}
\setlength{\brackoff}{\dimexpr 0.25\wd1-0.25\wd0}

\newenvironment{bvector}%
  {\hspace{\brackoff}\begin{bmatrix}\hspace{\brackoff}}%
  {\hspace{\brackoff}\end{bmatrix}\hspace{\brackoff}}%

\begin{document}
$\begin{aligned}
    \vec{x}\ '(t)   &= \textbf{A}\vec{x}(t) + \textbf{B}\vec{u}(t)\\
    \vec{y}(t)      &= \textbf{C}\vec{x}(t) + \textbf{D}\vec{u}(t)
\end{aligned}\ \ \ \to\ \ \ 
\begin{aligned}
    \dot{\textbf{x}} & = \begin{bmatrix}
        2&1&1\\3&-2&-2\\1&1&2
    \end{bmatrix}\vec{x} + 
    \begin{bmatrix}
        2\\1\\2
    \end{bmatrix}\vec{u}\\
    \vec{y} & = \begin{bvector}0&-1&-1\end{bvector}\vec{x}\\
\end{aligned}$
\end{document}