Aside from the fact that no Catholic I have ever met has assurance of their salvation, it is simply not true that the Catholic church gives anyone any assurance of salvation.
The assurance we have of our salvation if through the Holy Spirit and from God Himself when He breathed out Scripture and told us so Himself.
Well, living among and worshiping with Catholics every day, I find that most are confident that God’s promise to them will be fulfilled.
Catholics do not run around scared all the time that they are not going to be saved. That is a fallacy. What Catholics do however, is constantly take stock of their lives and their faith striving always to remain in Christ and to obey His commands.
We do not live in fear, we live in faith.