Even if people don't worship Mary, many do believe they need to pray to her so she can give their prayers to God. 1 Timothy 2:5 clearly states that Jesus Christ is the one mediator between God and mankind

Christ being the one mediator between God and man does not exclude Christians from interceding for eachother. John was told to intercede for all men. If you truly hold to your personal interpretation of Scripture then you should not pray for anyone because you are mediating between God and man.
Praying to the saints was practiced by the first Christians and held in every age because they knew that the prayers of the righteous are powerful.

That... actually makes sense. Now, I do think there is a difference between praying *to* the saints and praying *with* or *for* the saints. The main issue is that Christians should not feel as though they themselves lack a personal connection to God and need to go through others. Through the sacrifice of Jesus, all who believe in Him are saints, a royal priesthood. There is nothing wrong with Christians praying on behalf of one another, but to forget that you yourself can bring your requests and your struggles to God is to miss out on a huge part of the gospel.

Bottom Line: We all have an idol, we all have something that takes the place of God in our lives and we need to lay that idol down and put God first... With that said, The worst idol you could have is one that is explicitly condemned and spelled out in Scripture....
Let's stop making excuses for any kind of idols in our lives and get rid of them all!

Notice the second part of the quote. "You shall not bow down to them or worship them"
These people aren't worshiping the statue. They're praying to what it represents. Assuming they're Catholics (That's probably a statue of the most Holy Theotokos), they're probably praying for her to pray for them.