Garage door/opener construction practices

Does the garage door hardware and opener have to be installed with angle iron and/or metal brackets? I know that most houses are installed properly, but once in a while you’ll see some constructed with 2 x 4’s. They work fine & such, but documentation supporting proper installation would be great. Does anyone have the manufacturer requirements or a good narrative regarding this?

Thanks in advance.

2 x 4’s are fine if they serve the purpose adequately.