Perhaps commenter Jas3.1, above, is on the right track. The gospel writers do not say it, but Jesus' "cross talk" was but one instance of perhaps many "difficult sayings" which they and the other disciples did not truly understand until Jesus had died, rose again, and been glorified (e.g., John 6:60 ff., where Jesus explained this difficult saying to His disciples, and some of them took offense and stopped following him, whereas to the others who kept following Jesus, this difficult saying did not truly make sense to them until months later).
Jesus' "triumphal entry" into Jerusalem was an incident which did not initially "click" with the disciples as being a fulfillment of an OT prophecy concerning Jesus:
"On the next day the large crowd who had come to the feast, when they heard that Jesus was coming to Jerusalem, took the branches of the palm trees and went out to meet Him, and began to shout, "Hosanna! BLESSED IS HE WHO COMES IN THE NAME OF THE LORD, even the King of Israel." Jesus, finding a young donkey, sat on it; as it is written, 'FEAR NOT, DAUGHTER OF ZION; BEHOLD, YOUR KING IS COMING, SEATED ON A DONKEY'S COLT.' These things His disciples did not understand at the first; but when Jesus was glorified, then they remembered that these things were written of Him, and that they had done these things to Him" (John 12:12-16, my emphasis).
And finally in this line of reasoning, Jesus had to "scold" Cleopas and his son(?) for not recognizing the importance and necessity of His cross death:
"'O foolish men and slow of heart to believe in all that the prophets have spoken? Was it not necessary for the Christ to suffer these things and to enter into His glory?" (Luke 24:25,26 NASB Updated).
I would even go so far as to suggest that Jesus' comment about entering His glory went right over the heads of the two disciples on the Emmaus Road! Later, however, after seeing Jesus ascend to heaven (assuming they were there on the Mount of Olives, near Bethany, which was a good 15-20 miles from Emmaus), they likely understood--then.
What I am leading up to with my reasoning (or "argument") is: the disciples were well aware of what the word cross meant and what it implied and involved. They certainly knew that the Roman government of the day had the authority and power to dispatch people (i.e., administer capital punishment) and had done so with John the Baptizer--although his death by decapitation was likely much, much quicker than Jesus' torturous death on a Roman cross!)
Did the disciples, then, fully realize the gravity of Jesus' use of the word cross? No, I do not think so. Intellectually, yes. Emotionally and psychologically, no. Much the same with us today. As professor Walter Kaiser observed in his book An Introduction to Hermeneutics (Grand Rapids: Zondervan, 1994, p.18):
"Earlier in . . . [Shakespeare's Othello] the duke of Venice and some senators are discussing recent news regarding a Turkish fleet, but there is considerable discrepancy regarding the number of galleys involved. The duke then says:
I do not so secure me in the error,
But the main article I do approve
In fearful sense (1.3.10-12)
What may baffle us about a passage such as this one is that all the words are familiar to us--indeed, even the meanings of those words [of] approximate modern usage--yet the total meaning seems to escape us. Unless we are quite familiar with Shakespearean literature, it may take us a while to interpret this statement correctly. In modern prose [we would say], '[That] . . . there is a discrepancy in the accounts gives me no . . . security; it is with alarm that I must give credence to the main point of the story.'"
As with 21st century readers of Shakespeare, the disciples understood intellectually the denotation of the word cross (Gk. σταυρός, stav̱rós), but not until after Jesus' death did they begin to comprehend fully Jesus' words about taking up their cross daily and following Jesus even to the point of being literally crucified themselves.
In conclusion, for believers today, the word cross has lost both its denotation and negative connotation, and consequently its power to shock us and galvanize us to action. I'm not suggesting we remove the word from Scripture and replace it with a different word. I am suggesting, however, that we remind ourselves frequently that what Jesus was saying in effect was,
"Unless you are willing to die to your naturally self-centered, self-absorbed life and become others-oriented, seeking to serve others both within and without the church, even as I did when I entered the world, then listen up! I came not to be served, but to serve and to give my very life as a ransom for many. If you are not willing to do the same, then you are not worthy of me. Stop pretending, then, to follow me if you're not willing to die to yourself, as I did. The student is not above his teacher. Nevertheless, paradoxically, I have also come to give you an abundant life. That abundance will quite naturally be yours only if and when you die to yourself" (content taken from a number of Jesus' sayings and adapted here).