I can think of two explanations: 1. you did not specify that you wanted developers with DevOp experience. 2. it is possible that the developers you hired had

I can think of two explanations: 1. you did not specify that you wanted developers with DevOp experience. 2. it is possible that the developers you hired had previously worked in much larger companies where infrastructure staff handled the deployment aspect. As a general rule, deployment depends on numerous factors, is it SaaS, in-house, cloud, hybrid? What technologies, what volumes, etc, etc? Except for trivial setups AWS and GCP require considerable expertise. If you don't want to hire a fourth person, you could specify your requirements for deployment and have one of your team train as a DevOp.