The problem with polling in safe states is finding someone to pay for the poll. Polls are paid for by campaigns or by the media. Campaign polls for districts in safe states happen all the time, but only get covered when the campaign lets the info out. Those polls will often include the top of ticket races to help the campaign judge coattails and crossovers. Media polls look for the story so they make focus only on a region or set of competitive districts that will interest their audience. They may also include the top race for comparison with the local districts featured in the story.
The bottom line is that polls are expensive and that investment has to be worth something to someone to commission the poll.
Very true, someone has to be willing to pay for it. The only reason California gets polled so much is because there are several large media markets who are willing to pay for it, although the numerous initiatives are another reason.
