Because unlike other smart phone tariffs that advertise with a monthly data volume contingency, Aldi Sad hides a hook here in fine print. 12 GBytes cover all the time of the tariff. That means you have 12 GB for all 365 days, If you surf excessively in the first month, things may go short in other months.
However, few surfers should be happy about the offer. Since basically Aldi Sad offers here a tariff of about five euros a month, which can also be paid in full for a year in advance. The Samsung Galaxy A10 offers an annual package of 159 euros from 21 November 2019.