Digital implementation of first order analog filter using bilinear transformation
The expected 3dB frequency is wrong because of radian conversion. With $s=j\omega$,
$$H(j\omega) = \frac{1}{1+\tau j\omega} $$
and $20\log_{10}|H(j\omega)|\approx-3$
when $\omega=\omega_{3dB}=\frac{1}{\tau}$. However $\omega=2\pi f$, so 
$$f_{3dB}=\frac{\omega_{3dB}}{2\pi}=\frac{1}{2\pi\tau}.$$
With $\tau=0.1\text{s}$, $\ f_{3dB}=1.59\text{Hz}$ as on the original plots.