The "extra attack" entry only shows attacks that apply to any weapon attack and target. The extra attack provided by features like the Ranger's Horde Breaker or the Warlock's Thirsting Blade are (as FA said) circumstantial: the extra attack only applies when a condition is met. For a Horde Breaker, the condition is another target must be within 5 feet of the original target. For Thirsting Blade, the attack must be made with the warlock's pact weapon. There are likely other circumstances like this that do not show up as a general "extra" attack and should instead be noted elsewhere. I hope this helps.