Can anyone please explain and/or help me understand this -

On Spark website it says I can buy a SIM card for $5.00, and under the "Additional usage costs" says that additional data is charged at $0.30c/MB.

However, on the Smart Prepay page, I'm told that  Casual Data Rate is 10MB is $1 per day.

How does one invoke the $1 per day usage??

Cheers,

R.