This is mostly due to local news stations being lazy and regurgitating copy without doing any work on their own. The way news works involves stories and information being piped from party to party. Much of it comes from the AP or major national news bodies. Having seen how the sausage is made for these small local outfits, they are often run on a low budget with limited staff, old equipment and little bandwidth for their own editorial work outside of specific local news. Anything larger is likely going to be a copy paste job. The same is true for the weatherman. He's mostly just reading what the weather service puts out.
Plus aren't a ton of local news stations owned by Sinclair? MBA Bean Counting 101 would suggest that if you owned 200 news channels across the country that the first thing you'd do is look for stories that are relevant across all (or multiple) channels then pay 1 person to write it once. Rather than paying 200 people to write the story 200 times.
You'd also likely want to implement standards around language use that would create a consistent product with broad appeal, limit an editor's ability to go off the rails and do something that would harm the brand image, and that limits legal liability.
No it’s not due to laziness. Most local news is now owned by conglomerates or hedge funds that are “streamlining” them, removing their journalists and circulating non-local stories from other sources they own. The vast majority of “local” news - print or television, has been bought up. Sinclair, digital first media, Gannett, Tribune, etc. all own vast swaths of the “local” news media landscape.
The problem there is consolidated ownership of local television. Sinclair and Nexstar own the majority of TV stations in this country that aren't owned and operated (O&O) by the networks themselves. Actual local television ownership is dwindling, and those stations lose network affiliation, because the networks would rather work with large station groups to get more money in retransmission fees (as stations getting paid more money by operators means that the networks can demand more money from all affiliates).
