Yes they could earn 4k or even more per month but that amount is not net payment after deduct all the gas, commission and needed maintenance.

I think that one is more towards taking item from the sellers and send to warehouse.

Depends on parcel  either by size or weight ranging from 1.50-12 each.

If u rajin and go early picking condos in the same area u can easily send 200 parcels a day.
But min 55 must be delivered per day.
Got bonus for rajin and day day send plus allowance. But allowance sikit. If not mistaken only 50 for phone and 150 for petrol if by car for whole month.

Flexible timing and can earn minimum 2k a month.