The environment they were flying in presents several challenges to maintaining a reliable control and video signal while flying. In such a populated area the noise floor is likely to be pretty high to start with.
The pilot is using 433mhz for control and 1.3ghz for video, so right off the bat you have an 800mw video transmitter within a wingspan (54"?) of the control receiver. The control radio is only outputting 500mw and is considerably farther away.
All the buildings close by make for a multipathing nightmare, but can be mitigated by the use of circularly polarized antennas. There is a lot of DIY involved in building one of these with plenty of opportunities for something to go wrong, they're really just hacked together from consumer-grade wireless security systems.
I hope you can see how these factors make it much more likely control could be lost and make your comparison seem pretty silly.
Radio reflection off a flat surface reverses the direction of rotation of a circularly polarized signal. A CP receiving antenna will reject them. A twice-reflected signal will go back to the original direction of rotation, but it is much weaker after two reflections.
I hope you can see how these factors make it much more likely control could be lost and make your comparison seem pretty silly.