log(a^b) = b*log(a) works when given symbols, but not when given numbers

[derivitaandrew]

This is good:

ln(a^b) - b*ln(a) // Expected: 0; Actual: 0

but for some reason, if you use numbers in place of a and b, the simplification no longer works:

ln(2^2) - 2*ln(2) // Expected: 0; Actual: -2*log(2)+log(4)

It will work if a or b is 1, or if b is 0, but not otherwise.