"then why not take your day of "rest" on Tuesday, or Friday, or Wednesday...? You argue that "Sunday" became the day to "commemorate the resurrection"..."
John 20:1 Early on the first day of the week, while it was still dark, Mary Magdalene went to the tomb and saw that the stone had been removed from the entrance. 2 So she came running to Simon Peter and the other disciple, the one Jesus loved, and said, “They have taken the Lord out of the tomb, and we don’t know where they have put him!”
John 20:19 On the evening of that first day of the week, when the disciples were together, with the doors locked for fear of the Jewish leaders, Jesus came and stood among them and said, “Peace be with you!”
Matthew 28: After the Sabbath, at dawn on the first day of the week, Mary Magdalene and the other Mary went to look at the tomb.
Luke: 24:1 On the first day of the week, very early in the morning, the women took the spices they had prepared and went to the tomb. 2 They found the stone rolled away from the tomb, 3 but when they entered, they did not find the body of the Lord Jesus. 4 While they were wondering about this, suddenly two men in clothes that gleamed like lightning stood beside them. 5 In their fright the women bowed down with their faces to the ground, but the men said to them, “Why do you look for the living among the dead? 6 He is not here; he has risen! Remember how he told you, while he was still with you in Galilee: 7 ‘The Son of Man must be delivered over to the hands of sinners, be crucified and on the third day be raised again.’ ” 8 Then they remembered his words.
Many people who are required to work on Sunday, do in fact choose other days. And good for them. They are still putting a day aside for rest. You're the one hung up on legalistic custom. Paul taught against that. The early believers met on the first day of the week to celebrate the Agape Feast, because they were in better position to know what day Jesus rose than you. The actual witnesses were alive and speaking to them at the time.