There were other reasons why countries didn't take in adventurers en masse. Instead of hiring permanent staff with high salaries, it was better to outsource the work to local adventurer guilds, which made more sense as a business. For companies that can operate without the adventurers guild or a nation that can clear monsters with their military, the status of adventurers were even lower.
According to the complaints of the counter lady, there were no adventurers in the Silian Theocracy. The status of adventurers in the Baharuth Empire became even worse after the current emperor ascended the throne.
Ainz purged the slight feelings of disappointment from his heart. Getting the job you wanted and realizing reality was different from your imagination was a common occurrence.