Same issue in two accounts, (one US on PT). Just added my phone on my personal account and asked my client to configure his. None of the accounts allow the creation of new apps although both phones were verified.
Furthermore, I’d like to echo the above - not all twitter accounts are personal accounts. Especially dev accounts. Why would a person create an app? And if they do, what’s the percentage of highly successful apps that are “one man show’s”? Isn’t it a dangerous bottleneck to funnel all relevant auth requests through one physical medium that can be stolen, lost or just miles away from where it’s needed? can it at least be optional?