It usually happens in 2 steps.
First step is that everything gets connected to the LAN and you can only access the PLC network from within the building’s network. Then some time later, management finds out that keeping someone on-call to go out costs a fortune, so they request that access be made so they can make the change from anywhere.
The IT team argues security, but no new hardware can be provisioned and a developing a new process is too hard. Then the magical phrase is uttered: “Just make it work”. So IT punches a hole in the firewall, adds a NAT rule, and job done.