Your first example isn't correct. As with the existing WDRP emails that people receive, registrars can batch the verifications. Also, verification doesn't need to be done on a domain-by-domain basis, but on a contact-by-contact basis, thus if all 200 domains use the same one contact in all roles, only one verification needs to be done.
Of course, if your registrar doesn't manage contacts as separate objects from domains (and some don't), they yeah, you'll end up getting a boatload of verification emails.
You'll also start finding a bunch of registrars doing email address checks to ensure deliverability before any registrations or contact updates are performed: this is for the customer's good and the registrar's good.
Registrars have to make a best effort to contact the customer by email. That means that if the email does bounce initially (due to DNS issues, full mailbox, &c.), it's up to the registrar to try again until the grace period expires.
Your second one isn't correct: if your contact has already been verified, there's no need to verified again. It's only if the contact is new or updated that verification needs to be done.
In the third case, you should be using roles, not individuals. Mail aliases were invented for a reason: no one person should be receiving these emails, so it's really your own tough luck if you're a business and you're not ensuring that there's somebody always able to receive and process the emails. Moreover, verification happens when a contact is created or updated, so it should be an address with somebody immediately able to process the verification request.
As far as my ability to write authoritatively on the subject goes, I'm the development lead for a registrar, and implemented most of our domain management system myself.