Never thought about it, nor bothered me before, but with the upcoming sensitive referendum, it seems to me to be prudent to remove, not just bibles and crosses, but everything, turning all the polling stations into uniform blank office like areas.
It would also be prudent imo to change the locations of polling stations to the local Hall, rather than the school, as the study referred to in the article indicates that polling in schools can indirectly affect the result, even in less contentious referendum.
http://www.thejournal.ie/bible-referendum-3791712-Jan2018/https://www.gsb.stanford.edu/faculty-research/working-papers/can-where-people-vote-influence-how-they-vote-influence-polling