i got friends who work for splash damage and ubisoft , what Jonybat says is right these days.
The last time any company really employed testers was when things like high speed broadband was not the norm, think playstation 1 era. If wipeout was released with some hideous bug in it you couldnt download a patch or fix, there was no internal storage on the ps1, you basically had to recall every sold disc, and send your customers new ones, this was expensive, so you hired testers.
Nowadays you can sell pretty mucch anything to people and having to download a few gigs of patches after sale is no big deal, High speed BBand and storage being so cheap means you dont have to hire testers, you can actually get your customer base to test it all for free.