Could you talk us through this one? I am interested in the equation of "above one atmosphere" to between 0 and 1.

I’m not OP, but the startup ethos of the last few decades has been to move fast and break things, fake it til you make it, and generally operate on the bleeding edge to deliver incredible products (and, occasionally non-credible, cough Theranos).

My concern would be that the team would cut safety corners until the probability of success just barely rises above some threshold, rather than engineering everything to have as low a risk as is feasible. Is 0-1atm easier than 1-infinity atm? Yes, but that just means you can cut more corners.

I buy it. OP's comment struck me as interesting, because the "above 1atm" value turns out to be about 300atm; designing a pressure vessel to sustain a 300atm pressure difference is much more challenging than one to withstand 1atm, which is the case for these balloons. If we assume relative cost cutting due to cultural concerns, then the analogy makes sense.

1 atmosphere of pressure is a lot less than a few hundred atmosphere.

I also remember reading (but cannot find a reference) that it is easier to design a container for overpressure than to design it for underpressure.

In this case, I think providing a safety valve that fails before the container implodes violently may be a a good option (https://en.wikipedia.org/wiki/Pressure_vessel#Safety_feature...)