While the initial infection of a single workstation is often done by pray-and-spray phishing attacks, the common practice for modern ransomware attacks is that this is followed by a manually controlled attack by skilled teams, spreading throughout the network and servers is not done by an automated virus, it's done by controlled malware; and the encryption is manually triggered when they think that the preparations are complete to do maximum damage, backups have been disabled/corrupted, etc.

So they do target the extortion; already the decision to move on from that initial foothold will be based on the understanding of what institution it is and how much they would be willing to pay. In this case, they have intentionally targeted hospitals.