Why are most of the PLC systems built today considered to be proprietary in nature?

Most PLC (Programmable Logic Controller) systems today are considered proprietary because they are developed by specific manufacturers who tightly control both the hardware and software components. This proprietary nature limits interoperability with other systems and often requires users to rely on the manufacturer's tools and support for programming, maintenance, and upgrades. Additionally, proprietary systems can lead to vendor lock-in, where customers become dependent on a single supplier for their automation needs.