For digital signals, the fourier transform is taken along the unit circle of the Z-transform.
The equivalent to the Z-transform in continuous signals is the Laplace transform, but in that case the fourier transform is taken along the imaginary axis.

Why the difference? Why don't we take the z-transform along the imaginary axis in the DTFT?
An usual intuition to learn is that the real axis in Laplace are exponentials ($e^x$), while the imaginary are sinusoids $e^{iy} = \cos(y) + i\sin(y)$. Wouldnt that relationship hold in Z-transform too?