In other words:
1. Free trade is an unambiguously good thing according to practically every reasonable school of economics. In fact, Milton Friedman and everybody to his right argued that it would be smartest not to bother with free trade treaties, and just abolish trade barrriers unilaterally. That is obviously not tenable politically, so:
2. Free trade agreements are signed. But free trade does not just mean lowering trade barriers. There are also the dangers that a country might "cheat" - for example, subsidize a domestic industry to make it more competitive (basically, a hidden tariff), or impose regulations such that they would disproportionately impact foreign companies. For example, Israel at one point had a rule that imported ketchup bottles needed to be of a certain specific size, making it impossible for companies to use their existing bottles. This, while not technically a 'tariff' served to somewhat protect existing Israeli katchup makers from competition.
3. Other things that are often included in these agreements are equal access to non-defense bids for government contracts, and protection for foreign companies against unreasonable government action, seizure, etc.
4. Obviously , the treaties that result are complex and elaborate, and therefore international organizations are needed to resolve the conflict, such as the WTO court or similar groups.
These are our three alternatives
1. Free-trade treaties like this one.
2. Unilateral free-trade (not happening).
3. Protectionism.
Choose.