Tell that to these guys:

https://github.com/uavpal/beboptwo4g/wiki/faq#latency

Typically for direct connections (see this FAQ entry), the latency is around 50 ms. The pre- and post-processing of the live video stream is more than that, which you will also experience when flying in the original set-up (over Wi-Fi).

For more staged setups, there’s always MAVproxy