Why some engines do not have camshaft bearing?

Some engines do not have camshaft bearings to reduce complexity and manufacturing costs. In these designs, the camshaft may run directly in the engine block or cylinder head, using machined surfaces to support the camshaft instead of separate bearings. This approach can also save weight and space, making it suitable for certain applications, particularly in smaller or simpler engines. Additionally, it can enhance oil flow and reduce the number of parts that can wear out over time.