It's actually really hard to certify vehicles before use when they're novel vehicles. Try reading vehicle safety standards if you want proof of how complex it gets.

Good regulation balances the need for innovation vs the need for public health and safety. We can argue about the right balancing point all day, and people certainly will. But there's no simple solution on either side.

I agree there is no simple solution. But I'd prefer not to die, to prove to you that experimental submarines need regulation.

How is this a deniable point?

We are conscious enough as humans to not require death to change beliefs.