From first hand experience, it is much harder to maintain a FOSS environment. It feels like putting more on the line. And I cannot deny that I do it partly out of ideological reasons.
So I can totally imagine people being fired for getting in over their heads and messing something up, maybe repeatedly.
On the other hand, I've seen techs be banned from a client environment while dealing solely with proprietary software too.
I would disagree it's harder. It's trepidatious, but that's not the same.
We're in the middle of taking all our internal apps talking to a single huge Oracle database, and giving each app its own cluster of two PG boxes. Nothing has to play nice with anything else - that alone suddenly makes life ridiculously easier.
We have expensive paid Oracle support, who do PG as a sideline. But we've yet to have occasion to call them about PG.
I've been in a similar situation, a story I love to re-tell because it feels like a victory for open source.
We asked Oracle for a quote for two replicated mysql servers for HA. Because they were VMs we got a quote for 3 years that was 410,000 SEK (almost $50k). So we built our own replication solution with mariadb for free.
If you need support, there's nothing wrong with buying support, even quite expensive support. I'm sure Oracle would have provided the some of best MySQL support available.
But yes, it's good to have the option of doing it yourself :-D
(For our few services that run on MySQL, I'm really hanging out for MariaDB to make it into Debian and hence Ubuntu, which is what we run on live - a mix of 12.04 and 14.04. Oracle runs on our last two remaining Sun Niagara SPARC boxes. We will be killing our last Oracle this year.)
So I can totally imagine people being fired for getting in over their heads and messing something up, maybe repeatedly.
On the other hand, I've seen techs be banned from a client environment while dealing solely with proprietary software too.