How commercial companies decide which programming language/s to use is something of a dark art.

Companies are as varied as people, perhaps more so.

For many companies, their IT systems are a disparate collection of software which was created, or more likely bought in off the shelf, to solve a particular need. Others took a more holistic approach all along but there is always going to be the temptation to feel that something newer might just do the job better. Not just software or languages; the same feeling appears in many areas of life. So ultimately it boils down to the importance placed on IT within a company and the perspicacity of the management about the challenges of developing and maintaining that software.