Neutron stars do contain protons and electrons. It’s a misconception that they’re 100% pure neutrons.
A well-known type of neutron star is a pulsar. These rotating objects have extremely powerful magnetic fields which can only be produced by the movement of electric charges. If they were purely made of neutrons there could be no electric charges to move, and thus no magnetic fields.
Neutron stars do contain protons and electrons. It’s a misconception that they’re 100% pure neutrons.
A well-known type of neutron star is a pulsar. These rotating objects have extremely powerful magnetic fields which can only be produced by the movement of electric charges. If they were purely made of neutrons there could be no electric charges to move, and thus no magnetic fields.