Some kids will potty train themselves while some other kids may need to be pushed in the direction of potty training because some kids are stubborn when it comes time to potty train.
My now 5 year old son eventually potty trained himself when he was 3 years old after he refused before that to use the potty so I gave up and put him back in diapers and a year later when he turned 3 he decided he didn't like being in wet diapers anymore and would remove the diaper and then decided to start using the toilet.
So he essentially potty trained himself after deciding he didn't want to wear diapers.
If a kid hasn't become interested in the toilet by age 4 then you really should push the issue but if they're under 4 then I wouldn't worry and let them learn at their own pace.