Learn English – Present Continuous and already

It is probably true that the mother is still pushing the daughter to do her homework.

However, the mother's pushing the daughter now does not provide a reason for the daughter's having done well on a past exam. That can only be attributed to pushing in the past. Consequently, the perfect is in order here.

Note that this is an experiential perfect, not a resultative perfect—it characterizes the pushing as an element in the mother and daughter's current shared experience. The resultative burden is carried by the preposition because, and in a formal argument this would call for a simple past or past perfect (and in fact, most US speakers would probably employ a simple past here: "You got an A because I always pushed you."). But that sort of precision is unnecessary in colloquial contexts; in the context of a present or perfect in the main clause the present perfect maintains temporal harmony between the two clauses—"You've {got / gotten} an A because I've always pushed you."

According to the Oxford Dictionary (meaning 1.3), we use a continuous tense with always when we want to talk about something that happens repeatedly and annoyingly.

Compare that with using always in the present simple (meaning 1.1) - at all times; on all occasions

I am always ready - At all times
I am always nervous when I have to speak before a large group of people - on all occasions

frequently is defined as regularly; habitually; often: we use it to talk about a number of separate instances that happen at regular intervals, and is only ever used with the a simple tense- as if we are talking about each instance separately.