It's as Nick_CT says... purely RED TAPE... Some countries cannot accept PayPal payments and some cant even accept credit or debit cards..... Bank Transfer is the only way to deal with these companies...
Just do your research BEFORE parting with your hard earned.... but if your concerns are with any of the well known companies often mentioned in this forum (ACE, HDD Surgery, Atola) then you really have no worries...

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East Anglian Data Recovery Services
http://www.eadr.co.uk"If it's your only copy - then it's not a backup!"