Currently local web content (i.e. html files stored on a local hard drive) is hard locked to use the same shields settings as default pages on the web, but these two categories of content are different enough from a security standpoint to warrant different security settings, and tying them together can require users to do a lot of extra work (e.g. Brave Shields interact poorly with local web content).
There are 2 ways I can think of to address this: one is to have default settings for all local web content alongside the existing default settings for web content. The other is to allow specific exceptions to be made for each local file individually, similar to how this is currently allowed on a per-web-page basis. Personally, I would be equally happy with either approach, but I can imagine situations where someone might strongly prefer the latter.