Pharaoh is specific about the travel arrangements. He thinks of the women. He thinks of the children. He thinks of the honor due an aged patriarch.
"Thou, Joseph, shalt appoint for the honour of thy father: therefore tell thy brethren, Do this. Take with you from the land of Mizraim wagons drawn by oxen, in which to carry your children and your wives, and bring your father, and come" (Genesis 45:19). Targum Pseudo-Jonathan preserves the phrase l'ikar d'abuchon — for the honor of your father.
The sages read this verse through two lenses. First, halakhically. Kibbud av, honoring one's parent, is the fifth commandment, but it requires practical expression. It is not enough to feel respect for a father. One must arrange wagons. One must provide transport. One must ensure the journey does not break the old man.
Second, symbolically. The Hebrew word agalot, wagons, is etymologically close to egel, calf. The midrash (Bereshit Rabbah 94:3) plays on this. Joseph sends wagons as a sign to his father that the last Torah topic they studied together, years earlier, was the ritual of the eglah arufah — the calf whose neck is broken when a murder victim is found outside a city (Deuteronomy 21:1-9). When Jacob sees the wagons, he will remember the study, and he will know the message is really from Joseph.
The detail is tender. A father and a son had been in the middle of a lesson when the boy disappeared. Twenty-two years later, the lesson is still unfinished. The wagons are both transport and an unspoken, we were not done yet, Father. Come finish with me.