Many people are not afraid of dogs and/or at least know enough NOT to kick out, run from them, or to any way “ESCALATE” a bad situation, unless they feel “cornered”.
You train your dog to walk nicely on a lead by getting a private trainer and perhaps – you may need differing equipment such as a harness or head halter. Many pugs have partially collapsed trachea or develop them, so collars are not generally “USED” on them.
Your dog runs up to people and barks or growls OUT OF FEAR or ANXIETY (an attempt to threaten and intimidate and make a BIG SHOW in order to “run them off” – not unlike a peacock making a BIG FLURRY of feathers, etc. to frighten off people). It may also be due to a lack of socialization (when young) – much of that is on YOU; aside from possibly buying a dog of a weak and fearful temperament. But any dog as a puppy could have been mitigated in his response to people, had you worked on it.
His MISBEHAVIOR is 100% INAPPROPRIATE and should never have been allowed or tolerated – BY YOU….. the owner!!! But you’ve allowed it (or encouraged it, by not correcting it). You’ve allowed a HORRIBLY misbehaved and unfriendly dog to harass & threaten people *OFF LEAD* which is ILLEGAL FOR A REASON!!!! It has lead to his ABUSE ==> he HAS been KICKED; due to your lack of control and LACK of training.
If I had an electric cattle prod, I’d be using on you – every time any of this happened….. until YOU were reformed. Get a private trainer and STOP taking this dog out OFF LEASH before you are fined – for it.