acid base - Why do diacidic and triacidic alkalis dissociate in one step?

My book states that dibasic and tribasic acids dissociate in water in two and three steps respectively but for diacidic and triacidic bases it states that they dissociate in one step. I do not know why.

For example:

$\ce{H2SO4}$ dissociates in water in two steps as follows: $$\ce{H2SO4(aq) <=> HSO4^{-} + H+}$$ $$\ce{HSO4^{-}(aq) <=> SO4^{2-} + H+}$$

but

$\ce{Cu(OH)2}$ dissociates in water in one step as follows:

$$\ce{Cu(OH)2(aq) <=> Cu^{2+} + 2OH-}$$

Why is this so. Why does not $\ce{Cu(OH)2}$ dissociate in two steps to form $\ce{CuOH+}$ in the first step and $\ce{Cu^{2+}}$ in the second step?