

There could be any number of reasons for this, but Discworld (which shares many parallels with Tamriel!) provides a humorous hypothetical, if not entirely plausible example of what may have happened in Tamriel:

The fact that the Thieves Guild is by this point an officially recognised entity (see Third Century) supports this, and it seems as though the behavior of the guild is in some way sanctioned, if not permitted by the wider authorities of Tamriel. As the Thieves Guild is a guild, operating like a union, there will be diplomatic and litigious implications of being a member, and identifying yourself as one.
