I think you’ll find that any issues with the actual master link failing are due to incorrect installation rather than a failure in the part itself. Think about it - why would a chain company risk the liability and not just offer the rivet master links?
I don't know the answer to this, TBH. Maybe they sell them because they know there's a niche of lazy people that will buy them.
Chain manufacturer RK state that the clip-type connecting link is intended for off-road use:
the link can be installed without the use of a special tool which makes field-repairs or in-pit replacement easier and faster. However, these chains have limited life-spans and, in the case of race bikes, operate in very controlled circumstances where inspections and parts replacement occurs regularly.
Rivet types "are mostly used for street applications":
and can see tens of thousands of kms.
I've seen people use the clip type and put a turn or two of safety wire on the clip to make sure it doesn't pop off:
I guess this makes them less likely to pop off but they're still not as safe as a rivet link. As if riding isn't already dangerous enough; why screw around with janky chain links?