No, your child's school is not that dangerous
Despite the propaganda you see about this on social media, school shootings are rare.
The Indiana state legislature is banning cell phones in schools, which is good. Of the arguments I have seen against it on social media, the "safety" argument is the most absurd. Students having smartphones is not going to do anything to stop a school shooter. If anything, making them less aware of their surroundings might put them in more danger than not having a smartphone. Schools all over the country have locked doors and school resource officers to protect students.
If a school was so dangerous that my child "needed" his cell phone to ensure his safety, my child would not be attending that school. If I could not find a way to educate them safely, they would not get an education at all. It would be better for them to be uneducated and alive than educated and murdered. If the state tries to send law enforcement to enforce truancy laws, the police had better send more officers than I have bullets, because I will do what it takes to protect my child, up to and including lethal force. I have no sense of proportion about this.
Or, alternatively, I do not believe you when you tell me your child's school is so dangerous they cannot leave their smartphone at home. Statistically speaking, the odds of your child being killed in a school shooting are very small. Look at the number of teens who graduate each year compared to the number who die in school shootings, as well as the number of school shootings compared to the total number of schools. Despite the propaganda you see about this on social media, school shootings are rare. If phones are necessary for safety, it would make sense for every teacher and employee to be mandated to carry a phone at all times, in addition to the office phone.
If you really believed your child was in that much danger, you would yank your child out of that school. You would meet efforts to force your child into a deadly environment with deadly force. If you would not protect your child's life, especially for economic reasons, then you are a bad parent.
What about when a child is sick? Whether a child should be sent home should be a decision made by the school nurse, not a student who calls home and decides to be a malingerer that day. Having parents go to the school to pick up their "sick" child will only create disturbances and disruptions, which is why we have school nurses in the first place. If anything, schools are likely to be overly cautious, especially in the wake of the COVID-19 pandemic.
In fact, I have seen a number of parents on social media whine about their children being sent home. "Oh, little Suzy threw up once and she is fine, why do I have to go get her?" The reason these protocols are in place, and were in place before COVID-19, is to protect other students and staff from contagions. Things like norovirus can spread very quickly, especially among children who may not have the best hand-washing routine. I do not want my child getting sick, and then getting me sick, so that you are not inconvenienced. If your child is sick, go get him.
Technology is a good thing and smartphones have improved our lives in a number of ways. Calendar applications are great for planning on the go, and restaurant apps help you order ahead of time. You do not have to be tied to a desktop to check your e-mail any more. This just barely scratches the surface. But like all technology, smartphones have their place. That place is not in class creating a disruption or serving as a distraction for students. Banning smartphones in school is a necessary step that should have been taken 10-15 ago, before things got to where they are now. It's not a hardship or a threat to your child's "safety." Be reasonable, and be a good example.