The batts arrived from supplier to assembly plant in bulk.

The assembly plant (T or H or P or whatever) don't charge each & every batt to 100% before putting them into ur car.

When u receive ur car, the batt's likely at 60-70% state of charge.

Then u use ur car for short distance drive 10-20km after every ignition. That's actually not enough to bring up the SoC.

So slowly..... voltage drop below 12.5V, ur car can't start.

U jumpstarted the car, drove to battery shop, the shop told u batt kong.

U paid for a new batt, the shop took ur old batt, charge it back & later sell to someone seeking a used batt for RM100-150.

If battery weak, should not kejap takde response, then suddenly can start and then die wut? Got something short?

Not really. I once experience car suddenly dead. I restarted and it could move again and drove to nearby workshop. Lucky it was near the workshop. Tested and found out alternator was dead.

When the engine is off, chemical reaction in battery will slowly recharge the battery. I restarted the car and drove home about 1km away. I was lucky it happened not yet far away from home.The next day went to spare part shop to order the alternator. Got it replaced two days later.

Typical ppl yang tak bersyukur.
So lucky 20mins to get ur tow truck, damn fast already. Normal waiting should be around 1hour-3hours.