Liability insurance just means rich people have guns. the people who would most benefit from guns for self defense, low income people in high crime areas, would be excluded from gun ownership due to excessive costs. The police also aren't the answer as they have no duty to actually protect you, and have shown repeatedly that they will simply wait for overwhelming force while a shooter is killing people.
Gun registrations just tell the government, or anyone who can access the registration where to get guns. Registrations don't stop anything and only serve to create more criminals from otherwise innocent people if they don't file paperwork on time. Also, in the U.S. any form of government list of people is heavily suspect regardless of guns, a vast majority of people simply don't want anything that can let the government easily track them. Social Security is barely tolerated for keeping massive amounts of seniors from starving to death, even then the creation of the SSN was hugely controversial.