I could have sworn I already had a ticket for this.

ts-node sits between tsc and node. Some flags are node-style flags, some are tsc-style flags. For example, a user might assume --showConfig is camelCase because of tsc --showConfig, but they might also assume node-inspired flags use hyphens, because that's what node does.

It is straightforward to support both, since there's no risk of ambiguity. We can document fully in one style but then clarify that both styles are supported.