Depends how far you are from a border. Then there is a need for a visa for the other country. Incidentals such as food and drink during your journey. If you have to stop overnight a hotel room is required. Time away from home that you could be doing something useful or even productive.
Haven’t been to Jomtien immigration but can appreciate it must be busier than many other immigration offices. My last 90 day report was in-person for same reason. The girl on the form checking desk filled out a TM 47 for me as she wasn’t busy. Very good service IMHO.
Some people believe checking-in online or at airport totems avoids this check by the airline. However, the departure gate staff know how you’ve checked-in so can (and do) stop you at the gate. I know this because that was where I was ‘deboarded’ and my next two boarding passes had already been cancelled.
I have been denied boarding and also deboarded on the second leg of a three leg flight. The check-in/gate agents told me I must have either a return/onward ticket or, ‘some sort of visa’. In my experience, airline staff aren’t aware of the various types of visas offered by different countries. For example, Thai Airways at Munich asked to see my visa. I showed them my latest retirement extension which they accepted. They should have asked for my reentry permit also because, without one, my extension was now null and void.
Sounds like the receipt of notification only. Shows the information you provided. You don’t have to do anything. Does the website indicate ‘pending?’. Next you should receive notice of approval or rejection. The approval contains the date your next report is due. It is this that you print and staple into your passport.