Maybe Loriot is not showing addresses of other providers (not showing data it cannot decipher)?
What packets do you see?
Even when a DevAddr prefix is assigned to a country-specific provider, someone in your neighborhood might just be using a random address. Even more: it might not even be LoRaWAN but just plain LoRa. The “trace” part of each received packet might give you some clues about what TTN is trying to do:
The network needs the secret network session key (NwkSKey) to validate the message integrity code (MIC) to even know if it’s LoRaWAN. TTN only knows that NwkSKey for TTN device addresses. Without that validation, TTN can only assume that the first bytes in a LoRa packet are even a LoRaWAN device address to start with.