Guns and More Guns

This topic is always interesting for me.  Being Canadian, and having lived in the US for a few years, I see how different the thinking and the laws are on this topic between the two countries.
In Canada, if a person wants to buy a gun, first you have to write and pass a safety test, and fill out a form (I am not sure WHAT exactly the form involves) in order to get a license to own a gun.  The license is called a Possession and Acquisition Licence or PAL.  It allows you to buy and own a gun but not carry one.  If you want to own a handgun or other ‘restricted’ firearm, then an additional test is required- then your PAL has a R on it that allows you to buy and own restricted firearms. (I again, don’t know which fire arms are Restricted or Non-Restricted)
But a person is still not allowed to CARRY a gun. Carrying a handgun in Canada without authorization is very illegal and there is virtually no way for you to get authorization to do so without having a job which requires it.
After you buy a gun, you have to register it with the RCMP. Buying a gun at a store does this automatically.  For private sales, you have to call the RCMP to register your gun.
You also need extra authorization to transport your firearm from one place (your home where it is registered) to another (a firing range- for example).
(I had to look this up!)
This differs greatly from the US.
How easy is it to buy a gun in the US?  Are Background checks performed?  Is there a waiting period?  WHO freaking needs a semi-automatic weapon??  I am not dissing anyone who has a gun in their home for protection (although that isn’t a good enough reason to own one in Canada) but seriously, who needs a semi-automatic??
Canada has had some notable mass shootings for sure – the 1989 École Polytechnique massacre, the 1992 Concordia University massacre, the 2012 Danzig Street shooting, the 2014 Edmonton killings and the 2017 Quebec City mosque shooting.
But when you take into account the sheer numbers of mass shootings that the United States has, and the number of people killed by these shootings, and the fact that often semi-automatic weapons are used--- HOW can anyone say that GUNS ARE NOT A PROBLEM.  I really don’t get it.

Did I miss any??
The 2017 Sutherland Springs church shooting, the 2017 Vegas shooting, the 2016 Orlando nightclub shooting, the 2015 San Bernadino attack, the 2015 Umpqua Community College shooting, the 2013 Washington Navy Yard shooting, the 2012 Sandy Hook Elementary School shooting, the 2012 Aurora shooting, the 2009 Binghamton shootings, the 2009 Fort Hood shooting, the 2009 Geneva County massacre, the 2007 Virginia Tech shooting, the 1999 Columbine High School massacre, the 1990 GMAC shootings,  the 1991 Luby's shooting, the 1986 Edmond post office shooting, the 1984 San Ysidro McDonald's massacre, the 1982 Wilkes-Barre shootings