To the bolded part: Thats not entirely true, because both the Turks and the Arabs see the nikkah as an engagement which they can break off anytime. Yes, they do acknowledge that when you break this “engagement” you are “divorced” yet its called as an “engagement” and not a “marriage/wedding” until they have the wedding party. Personally I think this whole during nikkah- no-rukhsati has developed only in the past 10-15 yrs, before that people wanted nikkah-rukhsati at same time .. or at least thats how it was where I come from. But nowadays you see them all during nikkahs just for the whole “halal” proces.
My brother had his nikkah done prior to his barat - about 6 months. The main reason was the Visa issue. My mamo had to leave his wife behind after the wedding with her family, because they hadnt applied for the visa and there were some issues like she was pregnant, difficult to travel and so on. Therefor my mum asked the brides family for a nikkah so that we could apply for visa. Thankfully the visa was granted to my bhabhi in time so right after rukhsati she could come along.