I'm generally pretty positive about working for the USPS, but I even I have a hard time encouraging new RCAs to stay if they have any other opportunities. I just trained a new RCA--an older woman, probably doesn't have a lot of alternatives. I asked her about her job history--she was vague about what she had done before, so I don't think she has a lot of skills to offer the marketplace, so the RCA gig is probably good for her. Previous to training her, I worked with a new sub who had left a job at Chik-fil-a. Again, the USPS is miles ahead of that sort of work, so a good fit for her.
We lost a very accurate (though not particularly fast) RCA before Christmas--she had been handling the books for her brother's business and he couldn't afford her anymore, so she left and came to the USPS hoping for stable, reliable work (Hah!). Anyway, she found another job easily when she realized the RCA job was not for her.