I've checked with the support team, and the reason this is currently only visible to the Agency Admin is that HighLevel doesn't want the sub-account to see the actual price for the plan, since we can upsell at the desired price we want. However, once the plan is applied to the sub-account, at least let them check the remaining triggers.

They have no access to view it at all, it is very inconvenient for them because they always need to get in touch with the Agency Admin to check how many triggers they have utilised.