Why is roaming still so messy across Europe?

Just did 1,800 km through Belgium, Netherlands, Germany and France in my ID.4 and used four apps plus two RFID cards. One rapid in France refused both cards and only accepted a QR code that needed a local phone number. Another pre-authorised 50 euros and held it for a week. I get that roaming exists, but the pricing still feels opaque, and Plug and Charge barely worked outside Germany. How are you all handling this? Do you just accept one network's higher rate for convenience, or is there a card or app combination that actually covers most of Europe without surprises?