Eyes Wide Open
Most County Council Oracle shops are there because the database underpins core applications, I've been working with Oracle since release 5 and the company approach has been reasonably consistent since then. Most councils now split the workload between the older - Oracle based applications and the new SQL Server based apps and have teams skilled in managing and operating both DB regimes.
What posters don't seem to understand is that these core apps are embedded in the business operation and the cost of change is crippling. Council IT teams are severely resource constrained running literally hundreds of niche applications supporting everything from (fairly) standard back office systems (finance , property, CRM HR&Payroll) to critical applications sup[porting the most vulnerable members of society in Social Care, Education, trading standards etc. Most larger authorities are capable of dealing with Oracle and Microsoft (who are just as predatory) and manage the estates within the licence constraints. this includes not installing the pretty optional products before including them in the site licence. Oracle approach to VM recognition is annoying but in reality most Oracle large Oracle installs are still running on Unix servers and the Oracle VM and containers works well there. what hasn't been mentioned is that Microsoft take a similar approach to licencing SQL Server. They only recognize hyper-V as a Virtualization environment but also insist that every core for every server which a A SQL VM may run on is licenced. This means that if you operate a private hyper-V cloud you have to pin VM's running SQL Server to particular hardware hosts which restricts recovery in the event of a hardware fail. Again it's a pain but the tech teams are aware and do manage this. On top of that the tight integration between COTS packages and Microsoft Office make it impractical to replace MS Office with Libre office for these application users and the enterprise licencing model makes an estate split between opensource and Microsoft products more expensive than licencing MS Office for the whole estate.