When WGs define vocabularies, they're sometimes inconsistent with the capitalization of either the codes or display names. (It's possible there could also be variation between the use of camelCase and dashes, though I don't have an example of that.) If we're not going to have a standard that says "always lower case" or "always upper-case" or "always UpperCamelCase", then the tooling should at least enforce consistency amongst the codes within each FHIR-defined code system.