A few hundred microseconds is not enough time to send an announcement at the low bitrates required for noisy channels, and then you need to multiply it by the number of cells in a collision domain. This is a hard limit of information theory and physics.

And it is possible for the vast array of computer scientists in the world to work on more than one thing at a time; this particular work was done by a small team, whose specialties are in any case not suitable for work on better open authentication/consent protocols.