433 MHz VS. Manhole Cover
There will be gaps around the manhole cover, either air due to sloppy fit, or in the concrete/bricks. The 2.4GHz exploits those gaps with its 100cm/(11 * 4) = 100cm/44 = 2.2cm quarter-wavelength to leak out.

The 433MHz, 6 times longer in wavelength, has exponentially tougher problem in "leaking out". 

EDIT Here is link to prior answer on shielding, explaining the exponential behavior.
Why are many IR receivers in metal cages?