Earlier quoted context omitted.
Mailgun does not owe you or anyone a free tier. Start charging your clients money to cover costs that comes with their business.
I think the ask is that we wished Mailgun did that from the start instead of creating messes later in the process.
e.g., I can set up their account and other technical parts after that, but I can't verify their mobile number (added since we started working with Mailgun), don't have their credit card details to put on file (same), and often end up agreeing to legal notices for them rather than asking them to complete signup (and stalling the project).