How to do a NOT URI with switch -glob

Without resorting to regular expression matching (which should be avoided), I believe there is no way to do the kind of negation that you are describing with a

switch

switch [HTTP::uri] {
    "/bar/*"    { pool blah }
    default {
        if { !([HTTP::uri] starts_with "/foo/") } {
            pool blah
        }
        else {
            pool default
        }
    }
}

or

if { [HTTP::uri] starts_with "/bar/" || !([HTTP::uri] starts_with "/foo/") } { pool blah }

then just set the VS default pool to "default". Unhappily, in this, you can't avoid the double-evaluation in the worst case.