I get more punctures on the turbo than I do on the roads. Most are caused by small bits of sharp iron filings lying around on the garage floor which don't get through road tyres but easily puncture the turbo tyre. If they did puncture road tyres I might be a bit more careful about sweeping the garage. The turbo tyre presumably picks up this detritus while the wheel is being changed. Also, the turbo wheel generally has an old, patched tube and I've had problems with the patches coming off - perhaps the glue melts with the heat build up.
Riding on the turbo is so mind numbingly boring that I actually welcome the distraction of a puncture and the opportunity to get off and fix it.