Here is why I am shocked. I always look at those that follow Judaism to adhere to their religion more than those of the religion I follow. I never see phones in use or even vibrate during our Sunday services.
I appreciate the fact that you are shocked for this reason!
I think if you walked into a shul vs houses of worship of other religions you would see the difference and also why this happens. The entire atmosphere is different, less formal, more homey, more individual. In the early days of reform Judaism one thing they pushed was having decorum in a shul similar to that of what you're used to. While that seemed positive on the surface, it wasn't, because a shul is not a church and isn't meant to be.
None of this is to defend cell phones or talking in shul, both of which deeply disturb me